One of the many things that (have or has) affected me was...? [closed]

Which is appropriate?

One of the most significant adversities that (have or has) affected me was …


Solution 1:

Both are correct. The difference is very clear, though it generally doesn't strike at once. Think again.

One of the most significant adversities that have affected me was …

(Many adversities affected me, one of them was …)

One of the most significant adversities that has affected me was …

(There were many adversities, one of them that affected me was …)

One of the most significant adversities that affected me was …

is another possibility.