Mendel observed that pairs of alleles were separated or segregated in gametes and that they were rejoined in fertilization. we know that pairs of are segregated in and then are rejoined through fertilization.

It’s probably the last choice. Radiation

Explanation:

Heat moves through empty space, where there is no matter by: Radiation

It’s probably radiation because...

Radiation = the transfer of heat via electromagnetic waves that occurs through empty space and places where there is no matter.

So your answer would be the last choice^^