Final answer:
Lymphoid and myeloid cancers are primarily caused by genetic mutations, often resulting from the effects of oncogenic viruses or environmental toxins. Viral infections by HPV, hepatitis B and C, and carcinogens like UV radiation and tobacco smoke contribute to these genetic changes.
Step-by-step explanation:
Lymphoid and myeloid cancers are primarily caused by b) Genetic mutations. While it is true that certain viruses, known as oncogenic viruses, can increase the risk of cancer through infections, the direct cause of these cancers is the genetic mutations that result from the viral infections or other carcinogenic factors. These viral infections, such as hepatitis B and C, human papilloma virus (HPV), and Epstein-Barr virus, are associated with a certain percentage of human cancers. However, environmental toxins, like UV radiation and substances such as tobacco smoke, also play a significant role by damaging DNA and causing mutations that may lead to cancer. Furthermore, some individuals may inherit genetic defects that predispose them to cancer.