Final answer:
In the absence of recombination, an organism with six homologous chromosome pairs can produce 64 genetically different types of gametes. So the correcct option is D.
Step-by-step explanation:
In the absence of recombination, an organism with six homologous chromosome pairs can produce 26 genetically different types of gametes. This is because during meiosis, each homologous chromosome pair separates, and the different combinations of chromosomes from each pair can result in different gametes. Therefore, the number of genetically different gametes is equal to 2 raised to the power of the number of chromosome pairs.
So, in this case, 2⁶ = 64 different types of gametes can be produced.
Therefore, option D) 64 is the correct answer.