What Is the Approximate Age of the Star Cluster in the H-R

What is the approximate age of the star cluster in the H-R diagram below? ( Hint: Main-sequence stars of spectral types between A and B have core supplies of hydrogen sufficient to last about 250 million years, between A and F about 2 billion years, type G about 10 billion years, and between K and M about 30 billion years.)

A) 200 million years
B) 2 billion years
C) 10 billion years
D) 30 billion years
E) The age of the cluster cannot be estimated from an H-R diagram of the cluster.