What Is the Period of a Wave Described by the Following

Multiple Choice

What is the period of a wave described by the following function? y(x,t) = (2.00 m) cos[(6.00 m^-1) x + (10.00 s^-1) t] + (2.00 m) cos[(3.00 m^-1) x + (5.00 s^-1) t]

A) 0.628 s
B) 5.00 s
C) 1.26 s
D) 10.0 s
E) This is not a periodic function, so it does not have a period.