Question

farming became more difficult in iraq in the 1970s because
severe drought struck the entire region.
insects that thrive on hot weather destroyed crops.
leaders lost the rights to water supplies in wars.
dams went up on the euphrates and tigris rivers.

Explanation:

In the 1970s, upstream dam construction on the Euphrates and Tigris rivers reduced the water flow available for Iraqi agriculture, making farming far more difficult. The other options do not align with the key historical water-related challenge for Iraqi farming in this decade.

Answer:

dams went up on the Euphrates and Tigris rivers.