The Population I stars of the Milky Way Galaxy are hotter than the Population II stars for what primary reason?

Question

A.
Population I stars are older than Population II stars

B.
Population I stars are larger than Population II stars

C.
Population I stars are younger than Population II stars

D.
Population I stars are smaller than Population II stars

Answer 1

The primary reason that Population I stars are generally hotter than Population II stars is:

C. Population I stars are younger than Population II stars.

Population I stars are typically younger and formed more recently from the enriched material of previous generations of stars, which allows them to have higher temperatures and higher metal content compared to the older Population II stars. Population II stars tend to be older and have lower temperatures and metallicity.