Explanation:
The number of hydrogen bonds in a DNA double helix between adenine (A) and thymine (T) is always equal to the number of hydrogen bonds between guanine (G) and cytosine (C).
Since adenine (A) pairs with thymine (T) with two hydrogen bonds, and guanine (G) pairs with cytosine (C) with three hydrogen bonds, we can calculate the number of hydrogen bonds in the given DNA fragment:
240 bases of adenine (A) would pair with 240 bases of thymine (T), resulting in 240 * 2 = 480 hydrogen bonds.
2260 bases remaining would pair with cytosine (C), and guanine (G), so the number of hydrogen bonds would be 2260 * 3 = 6780 hydrogen bonds.
Total number of hydrogen bonds = 480 (A-T) + 6780 (G-C) = 7260 hydrogen bonds.
Therefore, option A) 480 is the correct choice.
