Answer
(c) $0.5$
Work Step by Step
The energy subsidy of corn production is calculated by dividing the energy input required ($40$ kcal) by the energy content of the produced corn ($80$ kcal). The energy subsidy is $$\text{Energy subsidy}=\frac{40 \text{ kcal}}{80\text{ kcal}} = 0.5$$ The answer is (c).
