Okay, let's tackle this question. The user is asking about a genetic law related to allele frequencies remaining constant across generations. The correct answer is supposed to be one of the options A to D, but the options aren't listed here. Hmm.

First, I need to recall the fundamental laws in genetics. The question mentions the relative frequency of alleles staying constant. That rings a bell with Hardy-Weinberg equilibrium. The Hardy-Weinberg principle states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences. So the law here is the Hardy-Weinberg Law.

Now, why is this the correct answer? The law is based on the idea that in an ideal population with no mutation, migration, selection, genetic drift, or non-random mating, allele frequencies remain stable. The equation p² + 2pq + q² = 1 represents the genotype frequencies, where p and q are the allele frequencies. This principle is foundational in population genetics.

For the incorrect options, common distractors might include Mendel's Laws (like Law of Segregation or Independent Assortment), which deal with inheritance patterns in individuals rather than population-level allele frequencies. Another possible wrong answer could be the Law of Dominance, which is part of Mendel's work and not related to allele frequency stability. There's also the concept of genetic drift, which actually causes changes in allele frequencies, so that's the opposite of what the question is asking.

The clinical pearl here is that the Hardy-Weinberg equilibrium is a null hypothesis used to detect evolutionary forces. Students should remember that the five assumptions (no mutation, migration, selection, large population, random mating) must be met for the law to hold. If any of these are violated, allele frequencies can change, leading to evolution.

Wait, the user didn't list the options, but the correct answer is supposed to be filled in. Since the correct answer is the Hardy-Weinberg Law, the explanation should reflect that. Also, the structure needs to follow the user's specified sections. Let me make sure each part is covered concisely without exceeding the character limit. Need to check for any typos and ensure clarity for postgraduate students.

**Core Concept**
This question tests understanding of **Hardy-Weinberg equilibrium**, a foundational principle in population genetics. It describes how allele frequencies remain constant in an ideal population under specific conditions, such as no mutation, migration, selection, or genetic drift.

**Why the Correct Answer is Right**
The **Hardy-Weinberg Law** states that allele and genotype frequencies in a population remain stable across generations if five assumptions are met: random mating, no mutation, no migration, infinite population size, and no natural selection. The mathematical model (p² + 2pq + q² = 1) predicts genotype frequencies based on allele frequencies (p and q). This law is critical for studying genetic variation and detecting evolutionary forces.

**Why Each Wrong Option is Incorrect**
**Option A:** Likely refers to Mendel’s Law of Segregation, which addresses allele separation during gamete formation, not population-level stability.
**Option B:** Could be the Law of Independent Assortment, which describes inheritance of unlinked genes, not allele frequency constancy.
**Option C:** May refer to the Law of Dominance, a Mendelian concept

✓ Correct Answer: B. Hardy-Weinberg law