Answer and Explanation:
A. The correct answer is A. At the moment of conception, a male sperm enters a female egg, also known as fertilization. This occurs in the fallopian tube of the female reproductive system. The sperm carries genetic material from the male, including half of the baby's genetic information. The fertilized egg, now called a zygote, begins a series of divisions and travels towards the uterus for implantation.
B. The answer B is incorrect. At the moment of conception, only a single cell, the zygote, is formed. It takes weeks for the fetus to develop its body organs.
C. The answer C is incorrect. The term "term" refers to the gestational age at which a baby is considered full-term and ready for birth, usually around 37 to 42 weeks of pregnancy. Conception marks the beginning of pregnancy, but it does not determine the term status of a baby.
D. The answer D is also incorrect. Prenatal care refers to the medical care received during pregnancy to ensure the health of both the mother and the developing baby. Prenatal care begins after conception and usually includes regular check-ups, screenings, and guidance on maintaining a healthy pregnancy. It is an ongoing process throughout the pregnancy and does not occur specifically at the moment of conception.