Answer:
convict tang
Explanation:
macro algae is the producer. from the given choices convict tang is the only one which consume the producer. that means it is the primary consumer. if you have any doubts feel free to ask :p
I am pretty sure it is c. convict tang.
If you look at all of the answer and trace the arrows to what they eat, you can see that the convict tang eats the producer, macroalgae.
