The backbone of the DNA strand is a chain made of a regularly repeating pattern of
a. nucleobase - deoxyribose -nucleobase - deoxyribose
b. phosphate-phosphate-ribose-phosphate-phosphate-ribose
c. phosphate-phosphate-deoxyribose-phosphate-phosphate-deoxyribose
d. phosphate-deoxyribose-phosphate-deoxyribose