Question

which of the following is a compound?
crude oil
water
neon
steel

Explanation:

A compound is a substance made up of two or more different elements chemically combined in a fixed ratio. Water ($H_2O$) is composed of hydrogen and oxygen. Crude oil is a mixture of hydrocarbons. Neon is an element. Steel is an alloy (a mixture of iron and other elements like carbon).

Answer:

water