Answer:
c. 28
Explanation:
Plant A has a dipoid chromosome number of 12, so its gametes will have an haploid number of 6 chromosomes.
Plant B has a dipoid chromosome number of 16, so its gametes will have an haploid number of 8 chromosomes.
The new species C arises as an allopolyploid from A and B. An allopolyploid usually originates from the breeding of two different species.
In this case, a gamete from plant A combines with a gamete from plant B to form a hybrid with 14 chromosomes (6 from A and 8 from B). These chromosomes are unpaired, so the hybrid is sterile.
In order to become a fertile diploid individual of species C, the most common mechanism is polyploidization, where the genome duplicates. That way, the resulting plant C has a diploid number of 14 x 2 = 28 chromosomes, of which 12 are A and 16 are B.