Answer:
the act of taking great risks in the hope of making large profits
Step-by-step explanation:
Given that Speculation in business or investment relation is a term that describes a form of financial bargains that comes with a lot of high risks but at the same time with the probability of high returns in the end.
Hence, in this case, the best definition of speculation, which was a cause of the Great Depression is "the act of taking great risks in the hope of making large profits."