list the angels in order from smallest to the largest

The angle measurements depend on the side opposite to the angle being found. If the side is the least, then the angle measurement will be the smallest. If the side is the greatest, then the angle measurement will also be the largest.
With this knowledge, ∠S, ∠R, ∠T, or (B) is your answer
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hope this helps
the relation between angle and side is
angle opposite to largest side = largest angle
angle opposite to smallest side=smallest angle
so correct order is ∠S, ∠R , ∠T