Final answer:
The acidic part of DNA is the phosphate group. The name 'acid' in deoxyribonucleic acid pertains to the presence of this acidic phosphate group, making option (B) II Only the correct answer.
Step-by-step explanation:
The acidic part of the DNA structure is the phosphate group. DNA is composed of three basic components: a 5-carbon sugar (deoxyribose), a phosphate group, and a nitrogenous base. Among these, it is the phosphate group that is capable of releasing hydrogen ions, making the DNA an acid. The specific term for this is phosphoric acid. The sugar and the nitrogenous bases are not acidic in nature.
The phosphate in the DNA structure provides the DNA with its name - deoxyribonucleic acid, and thus the correct answer to the question is (B) II Only, since the phosphate group is the only acidic component among the given options.