Final answer:
An autohexaploid of a species with a diploid number of 12 (2n = 12) would have 72 chromosomes, calculated by multiplying the diploid number by three (6n = 6 x 12 = 72).
Step-by-step explanation:
The question refers to a situation where a species, referred to as Species A, has a diploid number of chromosomes expressed as 2n = 12. An autohexaploid is an organism that has six copies of its haploid number of chromosomes. Since a diploid organism has two copies (2n), an autohexaploid will have three times that number (6n). Therefore, to find the number of chromosomes an autohexaploid of Species A would have, you simply multiply the diploid number by three:
6n = 6 × (2n)
6n = 6 × 12
6n = 72
So, an autohexaploid of Species A will have 72 chromosomes. However, this option is not listed above. Assuming that 72 is the correct answer and there may have been an error in the choices, since none of the given options (a through d) matches 72.