Under what circumstances would something have a "protective effect"?

Under what circumstances would something have a "protective effect"?

a.The family circumstances of children influence the way children will manage their own intimate relationships as adults.b.Something about a specific experience (e.g., being married) confers advantages or benefits.c.Random changes in genes from one generation to the next result in increased fitness.d.Love leads to a strong desire to protect the object of affection