Answer: a) deoxyribose sugar
b) guanine
c) adenine
d) phosphate group
Explanation: A DNA is a double stranded nucleic acid molecule. The building blocks of DNA are the nucleotides. A nucleotide is consists of deoxyribose sugar, a nitrogenous base and a phosphate group. The nitrogenous bases found in DNA are Adenine, Thymine, Cytosine and Guanine. In DNA base pairing, Adenine pairs with Thymine while Guanine pairs with Cytosine. The structure of a DNA double stranded helix is like a ladder in which the bases form the steps or rungs while the phosphate group and deoxyribose sugar form the phosphodeoxyribose backbone. Deoxyribose is a pentose, a sugar with five carbon atoms.
