25 Soldiers fighting in the First World War were forced to dig trenches as protection from?

Trenches were used to protect soldiers from poison gas, giving them more time to put on gas masks.

Explanation:

what are local authorities doing to fix the problem

explanation:

what are local authorities doing to fix the problem

option d is correct. corroborated sources of historical evidence   is necessary to validate a claim about an event in history.

historians tend to use written sources, but audio and visual materials as well as artifacts are important objects that supply information to modern historians.

historical sources are usually divided into two categories: primary and secondary sources. depending on the historian's intent, some sources shift their designation. determining what type of sources toimplement, and the level of credibility and reliability of those sources, is a significant step in critical thinking for the historian.

explanation: