In hexaploid wheat where 2n = 6x = 42, the haploid (n) and basic (x) chromosome numbers are respectively:

1. The somatic number is 2n = 42, so the gametic (haploid) number n = 42 divided by 2 = 21. 2. The relation 2n = 6x = 42 gives 6x = 42, so the basic number x = 42 divided by 6 = 7. 3. Therefore n = 21 and x = 7. 4. Option A swaps the two values and the others miscompute, making them traps. 5. Hence the answer is B. _Source: Samacheer Kalvi (TN SCERT) Class 10 Science, Unit "Breeding and Biotechnology", p.304_