Question

When investors purchase a commodity, they believe

the commodity's price will go up after purchase.
the bank will pay interest to the investors.
the investors' employer will match the cost.
the commodity is guaranteed to make them money.

Answer 1

A. The commodity's price will go up after purchase.
They hope that at some point they will make money on their purchase.

Answer 2

When investors purchase a commodity, they believe - the commodity's price will go up after purchase.

The investors invest certain amount on a commodity, and believe that it's price will increase so as to benefit them. This is not guaranteed though but the investors believe in this because this is the only way they will make profit out of their purchase.