Cultivation of two or more crops simultaneously on the same field without distinct (definite) row arrangement is known as:

Correct option is D

Mixed cropping involves growing two or more crops together without any specific arrangement.

(a) Relay Cropping: Relay cropping involves planting the next crop when the first crop reaches physiological maturity or just before harvest. Example: Rice followed by linseed, lentil, black gram, or chickpea.
Advantages:
1. Efficient use of residual moisture and fertilizers.
2. Reduces costs of cultivation, fertilizers, and irrigation.
3. Requires less labor.
4. Early sowing minimizes pest, disease, and weed issues.
Disadvantages:
1. Higher risk of crop failure.
2. Difficult to harvest with machinery.
3. Shortage of skilled labor.
4. Increased pest, disease, and weed problems in some cases.

(b) Double cropping: It is multiple cropping system in which two crops are grown in sequence on the same piece of land in a year. e.g. Black gram-Jowar, Black gram Wheat, Rice-Gram, Groundnut-Wheat etc.

(c) Ratoon Cropping: : Practice of harvesting a monocot crop by cutting most of the above ground portion but leaving the roots so as to allow the plants to recover and produce a fresh crop in next season.