What is the difference between heterozygous and homozygous individuals?

Plant species A has a diploid chromosome number of 12. Plant species B has a diploid number of 16. A new species, C, arises as an allopolyploid from A and B. The diploid number for species C would probably be

a. 14

b. 16

c. 28

d. 56

If one species (2n = 10) crosses with another species (2n = 18), producing an allopolyploid offspring, what is the ploidy of the offspring?

a. 2n = 10

b. 2n = 18

c. 2n = 10+18 = 28

d. 4n = 36 +20 = 56