Select the Functions That Have Identical Graphs $y = \sin \left( 3 x + \frac { \pi } { 6 } \right)$

Multiple Choice

Select the functions that have identical graphs.
-(i) $y = \sin \left( 3 x + \frac { \pi } { 6 } \right)$
(ii) $y = \cos \left( 3 x - \frac { \pi } { 6 } \right)$
(iii) $y = \cos \left( 3 x - \frac { \pi } { 3 } \right)$

A) $\mathrm { i }$ and $\mathrm { ii }$
B) $\mathrm { i }$ , ii and iii
C) ii and iii
D) $\mathrm { i }$ and $\mathrm { iii }$