The correct answer is C.
The nitro group is a meta-directing group in electrophilic aromatic substitution reactions because it is an electron-withdrawing group. Electron-withdrawing groups destabilize the benzene ring by withdrawing electron density from the ring. This makes the ortho and para positions less reactive towards electrophiles, and the meta position more reactive.
Option A is incorrect because the nitro group decreases electron density at the ortho and para positions.
Option B is incorrect because the nitro group does not increase electron density at the ortho and para positions.
Option D is incorrect because the nitro group does not decrease electron density at the meta position.