Final answer:
Pellagra, a dietary deficiency disease, is caused by the overconsumption of maize or corn due to its low levels of niacin. It was prevalent in regions where corn was a staple food. Therefore, the correct option is 2.
Step-by-step explanation:
Niacin (vitamin B3) insufficiency in the diet is the cause of pellagra, a condition characterised by nutritional deficiencies. A staple grain in many places, especially in areas of Africa and South America, is maize, commonly referred to as maize.
Although maize does not naturally lack niacin, improper processing might cause issues when it is a major food component. Niacin is present in maize, but it is bound and not easily absorbed by the body.
Niacin is released and rendered more bioavailable when maize is treated with an alkaline chemical, as in the case of traditional processing techniques like nixtamalization.
Therefore, the correct option is 2.