Explain why serious economic problems might make people more willing to listen to the ridiculous ideas?

Fear

Explanation:

People get desperate. Fear is a motivator to many especially when times get tough. Corona is a good example. Shortages in the grocery store may propel a family to buy a surplus of goods even when they don't particularly need them. The fear of not being able to purchase food brings uncertainty. Serious economic problems would make people feel not prepared. While in the bigger picture: The many who buy out stores and goods they don't need at the moment, they become the problem in the first place.

a historian researching the immigration policies of the early 1900s would expect a source written today,rather than in 1910 to :

( a ) be more interested in objective data and statistics.