Answer:
"John hopes the sleeping bag will keep the den dark and the bear calm a bit longer."
Explanation:
John wants the bear to calm down, and he wants to keep the darkness within his refugee by covering the entrance with the sleeping bag, He is hiding from the bear because he wants to avoid being attacked by it.
From the options provided, the complete gerund phrase in the sentence is:
B. <span>hanging curtains or shades on a window</span>
Gerund is a word which is in its -ing form. It is derived from a verb but acts as a noun.