The total production of food grains (Initial) = t

The total production of food grains (Final) = t’ = 1.4t

Population (Initial) = n

Population (Final) = n’

Per capita food production (Initial) = t/n

Per capita food production (Final) = t’/n’ = 1.4t/n’

1.4t/n’ = t/n

=> n’ = 140n/127

Population increased by [(140n/127 – n)/n] * 100 = 10% (Approximately)

Option C is the right answer.