The community would start to fall apart. For example, with no flowers, there are no bees. With no sun, there are no flowers.
Another example is if there are no fish, there is nothing for the bears to eat. No bears, and the bunnies and other small animals would overpopulate.
Parkinson's I guess would inhibit parts of the synapses which produce or receive neurotransmitter substances such as dopamine or acetylcholine which are required to produces as EPSP excitatory post synaptic potential which is required for the propagation of nerve signals. so signals cant reach the conscious muscles as effectively causing the involuntary shaking of the muscles in people with Parkinson's
hope that helps
D is the correct answer: fungi cannot cure diseases