How would you describe the size of and distance between the earth, the moon, and the sun

The correct answer is - B. Thymine, cytosine, cytosine, guanine, adenine, thymine.

Explanation:

According to the base-pairing rule, the one purine binds with a specific pyrimidine always, the purine adenine (A) only pairs with the pyrimidine thymine (T)  and similarly, the purine guanine (G) only pairs with the pyrimidine cytosine (C) in DNA, and in RNA the purine adenine (A) binds with the only uracil.

Here, the bases are -

Adenine, guanine, guanine, cytosine, thymine,  adenine

the string of their base pair would be:

Thymine, cytosine, cytosine, guanine, adenine, thymine.