A person who brings goods illegally into the country

Answer: Option C

One word substitute is Smuggler.

Exporter: a person, country, or company that sends goods or services to another country for sale.
Importer: a person or organization that brings goods or services into a country from abroad for sale.
Smuggler: a person who smuggles goods.
Imposter: a person who pretends to be someone else in order to deceive others, especially for fraudulent gain.