The correct answer is option 3: vegetables and fruits.

Vegetarians rely heavily on plant-based foods as their primary source of vitamins and minerals. Vegetables and fruits are rich in essential nutrients like vitamins C, A, and K, as well as various minerals like potassium, magnesium, and folate.

Vegetables such as broccoli, spinach, kale, carrots, and bell peppers are packed with vitamins and minerals. Fruits like oranges, strawberries, apples, and bananas also provide a good amount of vitamins and minerals.

While options 1 and 2 mention specific food items like black gram, wheat, rice, and mustard, these alone cannot provide all the essential vitamins and minerals required by vegetarians.

Option 4 mentions soybean and milk, which are indeed good sources of protein and calcium respectively, but vitamins and minerals are more abundantly found in vegetables and fruits.

Therefore, option 3, vegetables and fruits, is the most accurate and comprehensive source of vitamins and minerals for vegetarians.