Answer:
The methyl group will already be present
Explanation:
You want to make 1-methyl-4-nitrobenzene.
The question is, "Do I start with the methyl group on the ring and then nitrate, or do I start with the nitro group on the ring and then add the methyl group?"
The methyl group is activating and ortho, para directing.
The nitro group is deactivating and meta directing.
You want a para-substituted product, so you choose to nitrate toluene, as in the reaction scheme below.
