The correct option is
A Activating groups decide the position of electrophilic aromatic substitution.
−OCH3 is ortho/para directing group due to +R effect.
Thus, the nitro group mainly attached to para-position instead of ortho-position due to steric hindrance at ortho position and -I effect of
−OCH3 group. The reaction is shown below:
Hence, option (a) is correct answer.