Answer:
D. mejores
Step-by-step explanation:
"Blusas" is plural referring to many shirts. If it's the best shirt, it's "mejor" but the best shirts is "mejores."
It's not "mayores" because that means older people, like elders.
It's not "peores" because that's referring to things that would be the worst.
And it's not "más" because that's more.