Answer:
A= stabilising selection, B= directional selection
Step-by-step explanation:
A:
stabilising selection is any type of force that pushes the population towards a mean trait .
B:
Directional selection, or positive selection is a mode of natural selection in which an extreme phenotype is favoured over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype. So imagine in your graph for be there are two different phenotypes, this type of selections drives the preference of phenotype in one direction so you end up with more individuals with that specific phenotype.