Which condition would be most conducive to the evolution of sexual reproduction and recombination?

A rapidly changing environment

Explanation:

The sexual reproduction is more advantageous to organism to survive in the harsh conditions due to the changes in the sequence of nucleotides of the genes which became a characteristic feature of the sexual mode of reproduction.

This process of changes in the sequence is known as recombination. The sexual mode or reproduction evolved in the last common ancestors of eukaryotes but it is known to occur in the prokaryotes also as they reproduce by conjugation, transformation and transduction.

The sexual mode of reproduction was evolved in the organism as a result of the change in the environment to survive and thrive in the environment.