Which of the Following Three Ordered Triples Are of the Given

Which of the following three ordered triples are of the given form below. $\left( a , a + 3 , \frac { 1 } { 2 } a - 5 \right)$ Triple I : $( 2,1 , - 6 )$
Triple II : $( - 1 , - 3 , - 8 )$
Triple III : $( 4,7 , - 1 )$

A) Only triple I and II are in the given form.
B) Only triple II and III are in the given form.
C) Only triple III is in the given form.
D) Only triple I and III are in the given form.
E) None of the triples are in the given form.