Answer:
A) Carson has chosen this word in the last sentence of the excerpt to express his apprehension.
B) The mood this word choice creates is tension as well as fear. The words "grim specter" create an uneasy mood somewhat like fear. Also this excerpt of the sentence proves the tension amid:
"has crept upon us almost unnoticed, and this imagined tragedy may easily become a stark reality we all shall know."
Step-by-step explanation:
da|\/|n
hope that helps ;)