you can check it by calculation from x and y components of field.Suppose x component is Ex=Eo Sin(kz-wt) and y component is Ey=-EoSin(kz-wt).So you may write Ex+Ey=0.This is an equ...
for positive z direction, the argument of exponential should have opposite signs for bothe kz and wt part. hence Option A or B could be answer. Now for circularly polarized light, ...