Which process must the cell undergo to have genetically different cells at the end of cell division

The correct answer would be crossing over that takes place during prophase 1 of meiosis 1.

Explanation:

Crossing over maintains genetic diversity within an organism population, permits different genetic recombination to be transferred from parents to their offspring.  

Crossing over of chromatids pair takes place in prophase-I, it is the very first phase of meiosis-1. In this phase, the 3rd subphase is pachytene in which genetic recombination occurs due to the formation of recombinant nodules.

Thus, the correct answer is crossing over that takes place during prophase 1 of meiosis 1.

some scientists like gregory adcock agree with thorne's theory of regional continuity.

others, like chris stringer and ian tattersall, believe thorne's results may be contaminated or misinterpreted.