Answer:
Societies with iron technology in A.D. 200 developed a wide range of technological advancements and innovations. However, if you are looking for two specific things, here are two possibilities:
1. Iron technology boosted agricultural output, cleared land, and facilitated complex societies.
2. Iron tools and weapons were superior to bronze and stone, enabling advanced metallurgy and refined art and decoration.
You updated your question, and although A is the only valid answer, if I had to choose two of the answers, I would choose A and C.