Answer:
D. Owls.
Step-by-step explanation:
In a food chain, the secondary consumer is one who feeds on the animal that feeds on the producer.
By looking at the food chain shown in the question above, we can see that the producer is the blueberry bush, which will be consumed by the mice. The mice had served as food for the owl, which had served as food for the bobcat.
As you can see above, mice are the primary consumer that feeds on the producer, the owl, therefore, is the secondary consumer since it feeds on mice.