**Core Concept**
The quickening, also known as fetal movement, is a significant milestone in pregnancy where the expectant mother first feels the movements of the fetus. This occurs due to the maturation of the fetal nervous system and the development of skeletal muscles.

**Why the Correct Answer is Right**
The correct answer, **B. 16-20 weeks**, corresponds to the typical gestational age range when women first experience fetal movement. This phenomenon is often described as a vague "fluttering" or "butterfly-like" sensation in the abdomen. The fetal movements become more pronounced as the fetus grows and develops, allowing the mother to detect them more easily. The exact timing of quickening can vary depending on factors such as parity (whether the woman has given birth before), maternal body habitus (body type), and fetal activity level.

**Why Each Wrong Option is Incorrect**
**Option A:** 12-18 weeks is too early for most women to feel quickening, as the fetal movements are still subtle and may not be noticeable to the mother.
**Option C:** 26 weeks is too late, as women typically experience fetal movement earlier in the second trimester.
**Option D:** 24-28 weeks is also too late, as quickening usually occurs before this gestational age range.

**Clinical Pearl / High-Yield Fact**
Remember that the timing of quickening can be influenced by multiple factors, including parity and maternal body habitus. Healthcare providers should take these factors into account when assessing fetal well-being and monitoring for signs of potential complications.

**Correct Answer:**
✓ Correct Answer: B. 16-20 weeks