A. Insects (living) carry seeds (living)to new places, which allow new plants to grow.
B. People(living) plant trees(living) in a city park.
C. A drought dries up a river(not living), so deer(living) have less water to drink.
D. A fungus(living) causes a grove of trees(living) to die.
The answer is C because river is the only not living(abiotic) factor in these case