Find the odd number / letters / word from the given alternative:

Tea
Cinchona
Rubber
Chalk

The odd one out is Cinchona.

Tea, rubber, and chalk are all natural products, while cinchona is a plant that is used to make quinine, a drug used to treat malaria.

Tea is a beverage made from the leaves of the Camellia sinensis plant. It is one of the most popular beverages in the world, and is consumed by billions of people every day. Tea is believed to have originated in China, and has been cultivated there for over 5,000 years. It was introduced to Europe in the 17th century, and quickly became popular there. Today, tea is grown in many parts of the world, including China, India, Sri Lanka, Kenya, and Indonesia.

Rubber is a natural polymer that is produced by the rubber tree. It is a white, sticky substance that is used to make a variety of products, including tires, shoes, and gloves. Rubber was first discovered in South America, and was introduced to Europe in the 16th century. It quickly became a valuable commodity, and was used to make a variety of products, including shoes, gloves, and waterproof clothing. Today, rubber is produced in many parts of the world, including Southeast Asia, Africa, and South America.

Chalk is a soft, white sedimentary rock that is composed of calcium carbonate. It is used for a variety of purposes, including writing on blackboards, making chalk pastels, and removing stains. Chalk was first used in ancient Egypt, and has been used for a variety of purposes ever since. Today, chalk is produced in many parts of the world, including China, India, and the United States.