I’m not entirely sure about what you’re asking but chargaff’s rule is the thing that states that the amount of each “letter” in DNA is equal to its pair. Guanine (g) pairs with cytosine (C) and the same with adenine(A) and thymine (T). I’m sorry my answer is so vague, but I hope it helps a little!
A.
Explanation: Because he learned it in previous years when it was different, now it becomes hard to learn the new information.
