The correct units for exporting foodgrains to other countries is
Metric tonne
Explanation for the correct option(s):
Option B: Metric Tonne
Explanation for the incorrect option(s):
Option A: Quintal is a unit of weight for kilograms
Option C: Gram unit of mass or weight that is used especially in the CGS system.
Option D: Kilometer is a unit of measurement equal to meters
Thus, the Metric Tonne is a metric unit of mass equal to kgs, Hence Option B is correct.