What possible problems where there with vanports oregon’s location

Vanport was dramatically destroyed at 4:05 p.m. on May 30, 1948, when a 200-foot (60 m) section of a railroad berm holding back the Columbia River collapsed during a flood, killing 15 people. The city was underwater by nightfall, leaving 17,500 of its inhabitants homeless.

Explanation:

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the effect of the ming leaders banning ships with more than two masts was that there was no further construction of ships masts, because there was a surplus. ming emperors disallowed foreign exploration

your answer would be (b)