Explanation:

A cash crop is a crop that is grown specifically for its commercial value rather than for personal consumption. It is cultivated and harvested for sale in the market, providing income to the farmers. In this context, let's analyze the given options to determine which one is not a cash crop:

Jute:
- Jute is a long, soft, and shiny vegetable fiber that is primarily used to make burlap, hessian, and other textiles.
- It is one of the most important cash crops in India and Bangladesh, contributing significantly to their economies.
- Jute is primarily grown for its fiber, which is used to make various products like bags, ropes, carpets, and mats.
- Due to its high demand and commercial value, jute is undoubtedly a cash crop.

Jowar:
- Jowar, also known as sorghum, is a cereal crop that is mainly grown for its grain, which is used for human consumption and animal feed.
- It is widely cultivated in India, Africa, and other parts of the world.
- Jowar is an important food crop but is not primarily grown for its commercial value.
- While it may generate some income for farmers, it is not considered a major cash crop like jute or other crops grown primarily for commercial purposes.

Groundnut:
- Groundnut, also known as peanut, is a crop that is cultivated for its seeds, which are rich in oil and protein.
- It is widely used in cooking, as a source of vegetable oil, and in the production of various food products like peanut butter.
- Groundnut is a cash crop that is grown for its commercial value and contributes significantly to the agricultural economy.

Sugarcane:
- Sugarcane is a tall perennial grass that is primarily grown for its sugar content.
- It is a major cash crop in many countries, including India, Brazil, and Thailand, where it is extensively cultivated for sugar production.
- The sugarcane industry plays a crucial role in the economy, providing employment and generating substantial revenue.

Therefore, the correct answer is option B: Jowar. While jowar is an important food crop, it is not primarily grown for its commercial value and does not have the same economic significance as cash crops like jute, groundnut, and sugarcane.