Experimental studies reveal that double-stranded DNA can exist in three different helical forms known as A, B, and Z DNA. Why do molecular biologists primarily focus on B DNA?

B-DNA is the helical form most commonly found in nature.

Explanation:

Even though there are three different helical forms of DNA, molecular biologist primarily focus on B-DNA because is the most commonly found in nature. A very small proportion of Z-DNA is found in negatively supercoiled DNA, and A-DNA is formed when the DNA is facing dehydrating conditions. However, B-DNA is the prominent and active form found in nature, therefore is the most studied.

The correct answer is - B-DNA is the most common form of the DNA present in the cell and a good approximation of the structure of DNA in the cell.

Explanation:

The B - DNA is a form of the DNA that is explained by Watson and crick by the double-helical structure model. B-DNA is the predominant form of the DNA out of the three forms of the DNA which are B-DNA, Z-DNA, and A-DNA.

B-DNA is is provide a good approximation of the structure of DNA in a cell and its most common form of DNA in a cell that makes it the most studied and focused form of DNA.

Thus, the correct answer is - B-DNA is the most common form of the DNA present in the cell and a good approximation of the structure of DNA in the cell.