Answer: Through variation.
Explanation: This is because during prophase 1 the homologous chromosomes lies side by side through a process called synapsis forming a pair called bivalents and come into contact at a point called the chiasma through which genetic exchanges take place. This enables the undesirable traits of the parent to be removed whereas the favorable traits of the parents are passed on to the daughter cell therefore it becomes better adapted to its environment increasing its chances of survival.