The type of crop which is able to fix nitrogen from air is:

The correct answer is (b). Legumes are able to fix nitrogen from air.

Legumes are a type of plant that have a symbiotic relationship with bacteria called rhizobia. These bacteria live in nodules on the roots of legumes and fix nitrogen from the air, making it available for the plant to use. This is a very important process, as nitrogen is a key nutrient for plant growth.

Wheat, coffee, and rubber are not able to fix nitrogen from air. Wheat is a cereal grain that is a major source of food for humans. Coffee is a plant that is grown for its beans, which are used to make coffee. Rubber is a material that is made from the sap of rubber trees.

I hope this helps!