You Observe Three Different Star Clusters and Find That the Main-Sequence

Multiple Choice

You observe three different star clusters and find that the main-sequence turnoff stars in Cluster 1 have spectral type F, the main-sequence turnoff stars in Cluster 2 have spectral type A, and the main-sequence turnoff stars in Cluster 3 have spectral type G.Which star cluster is the youngest and which one is the oldest?

A) Cluster 1 is the youngest and Cluster 2 is the oldest.
B) Cluster 2 is the youngest and Cluster 1 is the oldest.
C) Cluster 2 is the youngest and Cluster 3 is the oldest.
D) Cluster 3 is the youngest and Cluster 1 is the oldest.
E) Cluster 3 is the youngest and Cluster 2 is the oldest.