Final answer:
The recombination event has most likely occurred between genes 1 and 4.
Step-by-step explanation:
The correct answer is F. 1 and 4. According to the information provided, recombination between genes A and B is more frequent than recombination between genes B and C because they are farther apart. Since gene A is closest to gene 4 and gene B is closest to gene 1, a recombination event is most likely to occur between genes 1 and 4.