Karen and Max are opposite-sex fraternal twins.The primary sex characteristic that differentiates them first began to develop
A) at their conception.
B) about seven weeks after their conception.
C) about the fourth month after their conception.
D) about the sixth month after their conception.

Question

Quizplus · Accepted Answer

The primary sex characteristic that differentiates males from females (the development of either testes or ovaries) begins to develop about seven weeks after conception.

Karen and Max Are Opposite-Sex Fraternal Twins