Methane hydrates are
a. a potential new source of natural gas
b. the largest reserve of methane on earth
c. releasing methane as the arctic warms
d. all of the above

a. a potential new source of natural gas

b. the largest reserve of methane on Earth

Explanation:

Methane hydrate is a lattice of ice crystal in which the molecules of methane are trapped. The methane molecules are the chief constituents of the natural gas. This forms when the gas molecules produced after the decomposition process of the organic matter gets covered with permafrost. The trapped natural gas can be obtained by warming and pressurizing the lattice. The Arctic permafrost beneath the ocean floor is the source of methane hydrates. These are the largest reserves of methane on earth.

if they have a finite resultant

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.