Final answer:
The substances activated by carcinogens that cause uncontrolled cell proliferation and differentiation in the absence of stimulus are oncoproteins formed from oncogenes.
Step-by-step explanation:
Oncogenes are activated by carcinogens and cause uncontrolled cell proliferation, differentiation, and prolonged survival in the absence of stimulus. Oncogenes originate from proto-oncogenes, which are normal genes that regulate cell growth and division. When these proto-oncogenes are mutated or expressed at abnormally high levels, they become oncogenes. Oncogenes produce oncoproteins that lead to continuous cell division, even when it is not needed, mimicking an overactive accelerator in the cell's regulation system. In contrast, tumor suppressor genes function as the cell's brake pedal by inhibiting unwanted cell division. However, when tumor suppressor genes are mutated, they can no longer regulate cell division effectively, which can also contribute to cancer development. The role of apoptotic genes is to regulate programmed cell death, and alterations in these genes can prevent the elimination of damaged cells that should not survive. Angiogenesis genes are involved in the formation of new blood vessels, which can provide a growing tumor with necessary nutrients. However, it is the oncogenes that are directly associated with the promotion of cell proliferation in the absence of normal growth signals.
The correct answer to the question is B. Oncogenes.