I think the answer to this question is mountains
I’m just trying to help so hopefully this did help;-)
The correct answer is a testable idea.
A Hypothesis is a assumed explanation for a certain event or phenomenon. For a hypothesis to be accepted for scientific research, first and foremost, the hypothesis should be able to undergo research or testing. It must hold the element of being testable for it to be proven.
<span>The effect of presidential coattail describes when a popular president running for reelection brings additional party candidates into office. This effect is brought about by the popularity of the presidential candidate who brings in supporters that will also vote for his/ her party's candidates. This is in relation to the idiom, ride on coattails, which means riding on another person's success. </span>