Answer:
C) The amount of A is always equivalent to T, and C to G
Explanation:
Chargaff's rule was given by the Austrian chemist, Erwin Chargaff in late 1940s. It explains the composition of the four bases i.e. Adenine(A), Guanine(G), Thymine(T) and Cytosine(C) in a DNA molecule. According to it, purine and pyrimidine bases are always found in 1:1 ratio in a DNA molecule. A and G are purine and T and C are pyrimidine bases and a purine always forms a pair with pyrimidine base hence the amount of A will always be equal to T and amount of G will always be equal to C. This rule forms the basis for the Watson and Crick pairs in DNA double helix model.
B. comet
comets only have tails because the sun is shining its light on the ice and dust behind the comet