The correct answer is (c). Khair (Catechu) is a tree of the sub-tropical forest. It is a deciduous tree that grows in tropical and subtropical regions of Asia. It is a member of the Fabaceae family and is closely related to the tamarind tree. Khair trees are known for their hard wood, which is used in construction and furniture making. The bark of the khair tree is also used to produce a dye and a tannin.
Sub-tropical forests are found in regions that have a warm, temperate climate. These forests are characterized by a mixture of deciduous and evergreen trees. The deciduous trees lose their leaves in the winter, while the evergreen trees retain their leaves year-round. Sub-tropical forests are home to a variety of wildlife, including deer, monkeys, and birds.
The other options are incorrect because khair trees do not grow in those types of forests. Sub-alpine forests are found in high-altitude regions, while cool-temperate forests are found in regions with a cool, temperate climate. Temperate forests are found in regions with a warm, temperate climate.