What is true about main sequence stars? A. They are older than white dwarfs.
B. They are older than red giants.
C. They are all newly born stars.
D. They are middle-aged stars.

Once an egg cell is fertilized by sperm, the cell then, as the embryo develops, it receives nourishment and eliminates wastes by transferring substances from its blood to its mother's blood. a. becomes a fetus immediately and exits the womb b. begins to divide and implants itself in the wall of the uterus c. remains in the uterus without dividing for several months d. travels back to the ovaries until the fetus is developed