Answer:
Option (b) is correct.
x = 45°
Step-by-step explanation:
Given: Figure 
We have to find the value of x 
Consider the given figure.
Since, SRV is a straight line and angle on straight line is 180°
Thus, 
∠SRV = 180°
also, ∠SRV  can be written as ∠SRT + ∠TRV
⇒ ∠SRT + ∠TRV = 180°
x + 3x = 180 
⇒ 4x = 180 
Divide both side by 4, we have,
x = 45°