Please help!!!!:

Mrs. Greenhaus has a six-sided number cube and a spinner. The number cube has the numbers 1 through 6 on its faces, and the spinner has four equal regions with blue, red, yellow, and green each in a different region. This tree diagram represents the outcomes of rolling the number cube and then spinning the spinner.

What is the probability of rolling an even number and landing on blue?
A.1/2
B.7/8
C.1/4
D.1/8