If a grasshopper is eaten by a frog, the energy transfer will be from (c) primary consumer to secondary consumer.
Explanation: Grasshoppers are primary consumers because they eat producers (plants). Frogs, in turn, eat grasshoppers, making them secondary consumers.
Why other options are incorrect:
(a) producer to decomposer: This scenario would only occur when a dead grasshopper is being decomposed by bacteria or fungi.
(b) producer to primary consumer: This is incorrect because the energy transfer has already happened when the grasshopper eats the producer (plant).
(d) secondary consumer to primary consumer: This is the reverse of the correct energy flow.