## Core Concept
The Oedipus complex is a concept in psychoanalytic theory that describes a child's desire for the opposite-sex parent and feelings of rivalry with the same-sex parent. This phenomenon is a key aspect of **Freudian psychoanalysis**. It is named after the character Oedipus in Greek mythology, who unknowingly killed his father and married his mother.

## Why the Correct Answer is Right
Sigmund Freud, an Austrian neurologist and founder of psychoanalysis, introduced the concept of the Oedipus complex. According to Freud, the Oedipus complex occurs during the **phallic stage** of psychosexual development (around 3-6 years of age). During this stage, children become aware of their genitals and begin to feel desire for the opposite-sex parent. Freud believed that this complex is a universal experience and a critical aspect of personality development.

## Why Each Wrong Option is Incorrect
* **Option A:** Erik Erikson, a German-American psychologist, is known for his theory of **psychosocial development**, which proposes that individuals go through eight stages of development from infancy to adulthood. While Erikson's theory is also a developmental theory, it does not include the concept of the Oedipus complex.
* **Option B:** Jean Piaget, a Swiss psychologist, is known for his theory of **cognitive development**, which describes how children construct knowledge and understanding through active experience and social interaction. Piaget's theory does not include the Oedipus complex.
* **Option C:** There is no well-known figure associated with the Oedipus complex other than Sigmund Freud, making this option incorrect by default.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the Oedipus complex, according to Freud, is resolved through the process of **identification**, where the child adopts the values and characteristics of the same-sex parent. This concept remains a topic of discussion and debate in the field of psychology and psychiatry.

## Correct Answer: D. Sigmund Freud