Geometry

The correct answer is B.∠RST.

 

1. Recall the angle - naming convention:

When an angle is formed by two rays  and , the common endpoint of these two rays is the vertex of the angle. Here, the common endpoint is point , which should be in the middle when naming the angle in the three - letter format.

 

The first letter represents a point on one of the rays, the middle letter represents the vertex, and the last letter represents a point on the other ray.

 

2. Analyze each option:

A: In this name, the vertex is , but the vertex of the angle formed by  and  is , so this option is incorrect.

 

B: Here, the vertex is , and  and  are points on the rays  and  respectively. This is the correct name for the angle formed by