Variations arise due to:

The correct answer is: All of the above

• The process of evolution is how populations of organisms evolve through time. These alterations are caused by genetic differences.
• Different types of phenotypes can be introduced into an organism by genetic changes that change gene activity or protein function.
• The likelihood of a genetic variant being passed down to the following generation increases if a trait is favorable and aids the individual in surviving and procreating (a process known as natural selection).
• The beneficial characteristic becomes more prevalent in a population over time as generations of people with the trait continue to procreate, differentiating the population from an ancestral one.
• The population can occasionally diverge to the point that it is regarded as a separate species. Variants do not all have an impact on evolution.
• Only genetic variations found in egg or sperm cells can be passed on to subsequent generations and may aid in evolution.
• Natural selection cannot act on some variants that arise during an individual's lifespan in just a few of the body's cells and are not inherited.