Step 1: Understanding the Concept:
Banana (Musa species) varieties are divided into two primary economic groups based on consumption:
1. Dessert varieties: Eaten fresh when ripe.
2. Culinary/Cooking varieties (plantains): Starchy bananas cooked before consumption.
Step 2: Detailed Explanation:
Let us examine the primary classification of the given varieties:
Robusta, Poovan, and Rasthali are classic dessert varieties grown extensively across India.
They are sweet, low in starch when ripe, and consumed directly.
Monthan is a prominent cooking banana (culinary) clone of India.
It is highly rich in starch, has a thick green peel, and is used for preparing curries, chips, and various savory items.
Therefore, Monthan is a culinary banana variety.
Step 3: Final Answer:
The variety of banana belonging to the culinary group is Monthan.