In the figure given below PS is the diameter. Points P, Q, R, and T, S, R, are collinear. Then, \[{{120}^{o}}\] is equal to

• A.  \[{{360}^{o}}\]                              
• B.  \[{{90}^{o}}\]
• C.  \[{{90}^{o}}\]                                
• D.  \[{{270}^{o}}\]