Which is the immediate effect of being infected by last season's flu virus? A. get the last season's flu virus B. receive this season's flu vaccine C. Immune to last season's flu virus D. Produce antibodies that attach to this season's flu virus.

The answer would be C: immune to last season’s flu virus this would be that your immune system has already created anti bodies getting rid of the last season’s flu once the immune system has defeated a infiltrator it would create memory cells to be able to create the required anti bodies next time an invader like this would attack your immune system

Compound light microscope

Although i don't know what is the simulated system, starfish are predators that eat mostly  microalgae,  snails, sponges, bivalves, mussels and other small marine animals. removing starfish from any system would definitely increase this animals that they prey.