Questions: According to the base-pairing rules in DNA, which of the following must be true of a molecule of DNA? The amount of C= the amount of G The amount of C> the amount of G The amount of C= the amount of T The amount of C < the amount of T

The answer is the first one: the amount of $C=$ the amount of $G$.

Explanation for each option:

1. The amount of $C=$ the amount of $G$: This is correct. According to the base-pairing rules in DNA, cytosine (C) pairs with guanine (G). Therefore, the amount of cytosine in a DNA molecule must equal the amount of guanine.

2. The amount of $C>$ the amount of $G$: This is incorrect. Since cytosine pairs with guanine, their amounts must be equal, not greater or lesser.

3. The amount of $C=$ the amount of $T$: This is incorrect. Cytosine pairs with guanine, and thymine (T) pairs with adenine (A). Therefore, the amount of cytosine does not equal the amount of thymine.

4. The amount of $C<$ the amount of $T$: This is incorrect for the same reason as option 2. The amounts of cytosine and guanine must be equal, so cytosine cannot be less than thymine.

Summary: According to the base-pairing rules in DNA, the amount of cytosine (C) must equal the amount of guanine (G).