DNA and RNA contain four bases each. Which of the following bases is not present in RNA?

DNA and RNA contain four bases each. DNA contains four nitrogenous bases, namely Adenine (A), Guanine (G), Cytosine (C) and Thymine (T).

The nitrogenous bases in RNA are Adenine (A), Guanine (G), Cytosine (C) and Uracil (U). Thymine is not present in RNA. Thus, option (iii) is correct.

Options (i), (ii) and (iv) are incorrect because these nitrogenous bases are there in RNA.