Which of the following is one of the direct causes of cancer?
(A) Obesity
(B) Inadequate `O_(2)` supply
(C) Atherosclerosis
(D) Hypertension

Explanation

Transformation of normal cell into cancerous neoplastic cells may be induced by physical, chemical and biological factors or agents.
Cancer causing agents are known as Carcinogens.
Ionizing radiations like X-rays and gamma rays and non-ionizing radiations like UV cause DNA damage leading to neoplastic transformation.
The chemical carcinogens present in tobacco smoke have been identified as a major cause of lung cancer.
Cancer causing viruses called oncogenic viruses have genes called viral oncogenes.
Several genes called cellular oncogenes or proto-oncogenes have been identified in normal cells which, when activated under certain conditions, could lead to oncogenic transformation of the cells.