AT, GC
Explanation:
Adenine (A) pairs with Thymine (T).
Guanine (G) pairs with Cytosine (C).
A - T
C - G
T - A
T - A
G - C
C - G
hope this helps you!
Natural selection is the process by which individuals who are best suited to the environment tend to leave (on average) more offspring than others.
Evolutionary changes take place over many generations and through millions of years of natural selection. For the genes to survive, they must be among the strongest.
The development of the human embryo follows fertilization, and continues as fetal development. By the end of the tenth week of gestational age the embryo has acquired its basic form and is referred to as a fetus. The next period is that of fetal development where many organs become fully developed.