Question

why did oil-producing nations impose an embargo on the u.s. in
the 1970s?
to increase their own oil consumption
due to u.s. support of israel in a conflict
because the u.s. stopped exporting oil

Explanation:

The 1973 oil embargo by OPEC nations was a direct response to the U.S. providing military and political support to Israel during the Yom Kippur War. The other options are incorrect: the embargo was not about increasing domestic oil consumption, and the U.S. was not the one halting oil exports in this context.

Answer:

due to U.S. support of Israel in a conflict