Final answer:
It is true that most cancers arise from the activation of oncogenes and the inactivation of tumor suppressor genes. Oncogenes when activated can promote cell proliferation, and tumor suppressor genes when inactivated result in loss of cell growth regulation, both of which are necessary for cancer development.
Step-by-step explanation:
The statement that most cancers result from combinations of oncogene activation and tumor suppressor gene inactivation is True (A). Cancers frequently arise due to a series of genetic mutations that alter cell growth and division. These mutations typically involve both the activation of oncogenes (genes that can lead to cancer when mutated or expressed at high levels) and the inactivation or loss of function of tumor suppressor genes (genes that normally prevent cell overgrowth and maintain genomic integrity). Oncogene activation can lead to uncontrolled cell proliferation, while inactivation of tumor suppressor genes removes critical growth checks, further contributing to cancer progression.
A primary function of tumor suppressor genes is to inhibit the division and survival of abnormal cells. When these genes are mutated, their capacity to regulate cell growth is compromised, which can result in the accumulation of further genetic alterations leading up to cancer. Therefore, it often takes multiple mutations in several genes to transform a normal cell into a cancerous one, since cells usually have multiple layers of regulatory mechanisms to prevent such transformation.