You have arrived on the scene of an incident involving an explosion. People in the immediate vicinity are all experiencing runny noses and difficulty breathing. Some are having convulsions. You suspect a terrorist incident involving a:
A. biological agent
B. blister agent
C. nerve agent
D. blood agent

Nerve agent

Explanation:

A nerve agent is a chemical in which on exposure to humans affects the functioning of the nervous system. These chemicals are known to disrupt the process by which messages are transferred to the organs from the nerve. This disruption occurs by blocking the activity of acetylcholinesterase, which is responsible for the catabolism of a neurotransmitter, acetylcholine.  

On exposure to a nerve agent, the muscles of the body become paralyzed and early symptoms is production of excess mucous such as in runny nose, pupil constriction and also difficulty in breathing.

These agents are sometimes used in chemical warfare. Examples include sarin, tabun etc.

yes, because even though a theory has a  lot of evidence to support it, it is not always true