Final answer:
The number of chromosomes in the new species D formed by allopolyploidy between species A and species C with 2n=14 would be the sum of the diploid chromosome numbers of species A and C. Without knowing species A's chromosome count, we can't specify an exact number for species D.
Step-by-step explanation:
If species A were to hybridize by allopolyploidy with species C (2n=14) and produce a new, fertile species, D, we need to determine the number of chromosomes species D would have. Allopolyploidy occurs when gametes from two different species combine to form a viable offspring. When a normal gamete fuses with a polyploid gamete, the resulting zygote will have an addition of both species' chromosome numbers.
Given that species C has a diploid number of 14 chromosomes, and assuming species A also has a diploid state, if species A's diploid number is the same or different but close to species C, the resultant allopolyploid species D would likely have a chromosome number that is the sum of species A and C's diploid numbers. If both species were diploid and we assume species A's chromosome count is 14 as well (2n=14), the resulting hybrid species D would have 28 chromosomes (4n = 28).
However, without information about species A's chromosome number, we cannot determine the exact chromosome count for species D. We can generally say that the chromosome count of species D would be the sum of the diploid counts of species A and C.