Final answer:
The gene position that can be determined by examining the double-crossover class of a three-point cross is the middle gene.
Step-by-step explanation:
The gene position that can be determined by examining the double-crossover class of a three-point cross is the middle gene. In a three-point cross, three genes are being analyzed at once. When a double crossover occurs between the outer genes, the middle gene is the one that determines the crossover pattern. By examining the double-crossover class, we can infer the position of the middle gene.