Concept:
Crops are classified based on their primary economic use such as cereals, oilseeds, fiber crops, and spices.
Step 1: Crop (A)
• General term often referring to food crops.
• Here it matches with cereals.
Thus, A $\rightarrow$ III.
Step 2: Mustard (B)
• Oilseed crop.
• Used for extraction of edible oil.
Thus, B $\rightarrow$ I.
Step 3: Cotton (C)
• Fiber crop.
• Used in textile industry.
Thus, C $\rightarrow$ IV.
Step 4: Pepper (D)
• Spice crop.
• Used for flavoring food.
Thus, D $\rightarrow$ II.
Final Matching:
\[
A-III,\; B-I,\; C-IV,\; D-II
\]
\[
\boxed{\text{Option (B)}}
\]