Solution

Protooncogenes are the genes that regulate the normal functioning of the cell cycle (the orderly series of event that leads to the formation of daughter cells by parent cell and is under the regulation of several check points). Mutation in proto-oncogenes produces oncogenes that cause loss of control over cell cycle and uncontrolled and repetitive entry of cell in cell cycle thereby forming tumors. This makes option A incorrect. Option C is incorrect as carcinogenic mutations inactivate the check points and cause loss of control over cell cycle. Option B is incorrect as these mutations inhibit the telomerase inhibitor and thereby make the cells immortal. Telomerase enzyme is responsible for replication of telomeres to help cells to maintain the chromosome length. Option D is correct as carcinogenic mutations accelerate the synthesis of telomerase enzymes as inhibition of its synthesis may cause cell death due to gradual shortening of chromosomes during each replication cycle.