What are common causes of angina?

Angina is commonly caused by reduced blood flow to the heart muscle, most often as a result of coronary artery disease. This condition involves the narrowing of the coronary arteries, typically due to plaque buildup, which inhibits the proper blood flow. Physical exertion is another contributor, as increased activity requires more oxygen, and if the coronary arteries are compromised, it may lead to chest pain or discomfort known as angina.

In contrast, the other options presented involve conditions that do not directly affect the heart's blood supply. Respiratory infections and anxiety might lead to chest discomfort but are not direct causes of angina. Likewise, low blood sugar and dehydration can lead to various symptoms but are not associated with the heart's blood flow issues that characterize angina. Heat exposure and poisoning can cause other health problems but don't typically result in angina. Therefore, the combination of coronary artery disease and physical exertion accurately identifies the primary factors that lead to angina.