Answer:
Stimulus
Explanation:
The answer is stimulus. In plural it would be stimuli.
This could be two answers Water or Oxygen. I would go with water because it contains oxygen therefore making it a possible answer. Hope I helped. :)
C SHOULD BE THE CORRECT ANSWER BUT IM NOT SURR
Bacteria, hope this helps!
B is correct. Krypton is a noble gas which has a full outer shell of 8 electrons and is generally unreactive because of it.