Answer:
<em>yh thats true lol, ty for that very interesting fact</em>
The answer is A. Isotopes only differ in the number of neutrons in the nucleus of their atoms. Otherwise, all other subatomic particles are the same. The isotope with the more neutrons in its nucleus is therefore, heavier (have higher mass number). They share the same chemical properties but have slight physical differences such as boiling points with the heavier element having a slightly higher boiling point that the lighter element.
The phosphate group of one nucleotide bonds covalently with the sugar molecule of the next nucleotide, and so on, forming a long polymer of nucleotide monomers. The sugar–phosphate groups line up in a “backbone” for each single strand of DNA, and the nucleotide bases stick out from this backbone. The carbon atoms of the five-carbon sugar are numbered clockwise from the oxygen as 1′, 2′, 3′, 4′, and 5′ (1′ is read as “one prime”). The phosphate group is attached to the 5′ carbon of one nucleotide and the 3′ carbon of the next nucleotide. In its natural state, each DNA molecule is actually composed of two single strands held together along their length with hydrogen bonds between the bases.