A new mutation that arose in one copy of gene X in a somatic cell resulted in the formation of a tumor. Which of the following pieces of evidence best describes how the new mutation directly caused the tumor?

The correct option is Protein X normally stimulates cell division and the mutation created an overactive version of protein X.

Explanation:

Mutation can be described as any change which occurs in the genome of a person. The alternation by mutation might cause dreadful situations for a person or it might turn out to be beneficial.

In the scenario discussed in the question, it might be that the gene X in which the mutation arises produced protein which stimulates cell division. The mutation might have caused the protein X to change and become an overactive version. Hence, cell might uncontrollably produce Protein X causing cancer.