What is a string of volcanic islands that forms on the overriding plate

Two out of four offsprings have the yellow kernel phenotype.

Explanation:

The information that we have is that one parent's genotype is yellow bead (Y) and blue bead (B), and the other parent's genotype is blue bead (B) and blue bead (B).

Parent 1: YB

parent2: BB

If we make a Punnett Square, we can see that two out of four offspring will have the yellow phenotype.

  ║ B   ║ B   ║

Y║ YB ║ YB ║

B ║ BB  ║ BB ║