Answer:
Iron-work, salt, timber, and agriculture
Step-by-step explanation:
The Roman Republic had multiple natural resources which it used very well in order to have a strong economy. The iron was in abundance, so the iron-work was very well developed, thus the trade with iron tools and items was one of the most important. The salt was very demanded, so the abundance of salt deposits was used for trade with numerous parts of Europe. The volcanoes provided lot of fertile soil, some of which was heavily used for farming crops, some of which for domestic usage, some for trade, as well as lot of high quality timber. The timber was demanded a lot, especially in the Mediterranean region, be it for wood-works or as a material for building ships, which brought big profit tot he Romans.