Question

what is the primary mechanism through which freshwater mussels reduce turbidity in rivers
by absorbing and storing excess nutrients that cause turbidity
by producing chemicals that agitate sediment particles
by generating water currents that disperse sediments
by actively filtering and removing suspended particles from the water

Explanation:

Las mejillas de agua dulce son filtros activos. Retiran partículas suspendidas del agua, lo que reduce la turbidez. No absorben nutrientes causantes de turbidez, ni producen químicos para agitar partículas de sedimentos, ni generan corrientes de agua para disperger sedimentos.

Answer:

By actively filtering and removing suspended particles from the water