Check my answer: Which topic is suitably limited for a research paper?

AThe history of baseball and its greatest players
BThe home run record and batting average of Lou Gehrig ★★★
CWhy Lou Gehrig was forced to resign from baseball
DHow Lou Gehrig overcame difficulties to become one of baseball's greatest players

I chose b because there isn't much to talk about (limited). Is this right? Can someone explain if it's wrong?