How many linkage groups are found in a pea plant (Pisum sativum)?

The correct option is A 7
All the genes present at different loci on a single chromosome form one linkage group. These are inherited together as a unit from parents to offspring. Linkage group is equal to the total number of different chromosomes, or total number of haploid sets of chromosomes.
Pea plant is a diploid plant and has 7 pairs of chromosomes. Haploid number of chromosomes would be 7. Therefore, pea plants have 7 linkage groups.