Final answer:
The recombinant frequency of genes TE and X1 is found by dividing the number of recombinant offspring (45) by the total number of offspring (500) and multiplying by 100, resulting in a frequency of 9%.
Step-by-step explanation:
The recombinant frequency of two genes is used to estimate how often crossing over occurs between them during meiosis. In your question, 45 out of 500 offspring from crosses involving the two genes TE and X1 had recombinant genotypes. To calculate the recombinant frequency, you divide the number of recombinant offspring by the total number of offspring and multiply by 100 to convert the answer to a percentage.
45 recombinants / 500 total offspring = 0.09
0.09 × 100 = 9%
So, the correct answer is 9%, which corresponds to option (c). This suggests that the genes TE and X1 are on the same chromosome and experience crossing over at some frequency. If the genes were unlinked (on different chromosomes or far apart), you'd expect a 50% recombinant frequency. A recombinant frequency of 0% would indicate completely linked genes with no crossing over.