The correct answer is (d). Maize is used as a staple food in South-East Asia. It is a major cereal crop in the region, and is grown in many countries, including Thailand, Vietnam, Indonesia, and the Philippines. Maize is used to make a variety of dishes, including porridge, bread, and noodles. It is also used to feed livestock.
(a) Western Europe is not a major producer of maize. Maize is not a staple food in most Western European countries.
(b) Russia is a major producer of maize, but it is not a staple food in Russia. Maize is used to make animal feed and industrial products, such as ethanol.
(c) Middle Africa is not a major producer of maize. Maize is not a staple food in most Middle African countries.
(d) South-East Asia is a major producer of maize. Maize is a staple food in many South-East Asian countries.