Question

Leaves become modified into spines in
A. Allium
B. Gossypium
C. Opuntia
D. Pisum

Answer 1

Hint: Spine is the modification of leaves. It is due to the reduction in the surface area and minimize rate of water loss by evaporation and transpiration. Besides, they also provide protection to the plant from grazing animals.

Complete answer: The spine is properly modified, sharp-pointed leaf. That has a bud in its axil, and the spine occurs in the relative position of a leaf. Some of the spines are called "stipular spines" because they are modified into sharp-pointed stipules at the base of a leaf. Opuntia is a genus in the cactus family, also known as Cactaceae. The most common culinary species is the Indian is Opuntia. Most people use the term "prickly pear" to refer to this species.
Opuntia typically grows with flat, rounded cladodes armed with two kinds of spines; large, smooth, fixed spines and small, hairlike prickles called as glochids, that easily penetrate the skin and detach from the plant. Many types of pears grow into dense, tangled structures.
Opuntia occurs in the Peace River situated in western Canada almost to the tip of South America.
 In the Northern Hemisphere, the brittle prickly pear (O. fragilis) is one of the most northern-ranging cacti. Opuntia is used for treating diabetes, high cholesterol, obesity, and hangovers. It is also used for its antiviral and anti-inflammatory properties. The pectin fiber in the prickly pear helps decrease the levels of low-density lipoprotein (LDL) cholesterol, also known as “bad cholesterol”, in the body.
Thus, the correct answer is option C

Note: A cactus plant has spines instead of leaves, and this is nature's way to help the plant survive. The spines come in a variety of forms, such as Awl-like.