What event aided the further development of the airplane? the development of lighter steel increased industrial efforts for world war i political pressure advances made in automobiles advertising on the radio?

The one event that eventually had one of the major impacts on the influence of the advancement of airplanes was the World War I. To cite for example, starting in October 1911, Italy started to use aircraft for military purposes. Within a month, they realized that they could bomb enemy positions using airplanes, hence changing the direction of the airplane industry forever.

Therefore the answer among the choice is:

 increased industrial efforts for world war i

answer: because they get bored or smth idk

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: