Final answer:
The chromosome number in an allotetraploid produced from Species I and II, which have diploid numbers of 2n = 24 and 2n = 26, respectively, would be 50. This is calculated by doubling the sum of their haploid numbers.
Step-by-step explanation:
The question asks about the chromosome number in an allotetraploid produced from two species with different diploid numbers, 2n = 24 and 2n = 26. An allotetraploid results from the combination of the complete sets of chromosomes from two different species. Therefore, to find the chromosome number of the allotetraploid, we calculate it by doubling the sum of the haploid numbers (n) of both species (since each species contributes n chromosomes after gamete formation).
The haploid number (n) for species I is 24/2 = 12, and for species II is 26/2 = 13. Thus, the allotetraploid would have a chromosome number of 2 * (12 + 13) = 50. Therefore, the correct answer is (a) 50.