Answer:
b.)The ecosystem would be harmed as other phytoplankton-eating organisms would have less to eat.
Step-by-step explanation:
Introduction of zebra mussels will definitely harm the ecosystem because they are invasive. They impose a lot of threat to the native inhabiting species of the water bodies. They attach themselves to the native species and use them as anchors for their survival. By doing this, they make it very difficult for the native species to move, feed and breed. Not only this but also they compete with the native species who eat phytoplanktons as food because of which availability of food for the native species becomes limited.