According to Erwin Chargaff's rules for a double-stranded DNA molecule, which of the following relationships is universally correct?

Step-by-step solution

According to Erwin Chargaff's rules for a double-stranded DNA molecule, the amount of adenine ( A ) is always equal to the amount of thymine ( T ), and the amount of guanine ( G ) is always equal to the amount of cytosine ( C ). A = T and G = C Adding these two equations, we get: A + G = T + C This means the total amount of purines ( A + G ) is equal to the total amount of pyrimidines ( C + T ). A + G C + T = 1 Answer: A + G C + T = 1