The Armorer's Apprentice - Act 1 Side Quest
Closest Portal: Eirulan
Objective: Tell Apprentice Telinu an armor recipe
Reward: The correct answer gets you a piece of set armor; otherwise you get nothing
The Armorer's Apprentice is the very first Side Quest that you will come across in Dungeon Siege 2; it begins by speaking with Telinu on the Merchant's Terrace of Eirulan. In the town of Eirulan the very first terrace that you're given access to is the Merchant's Terrace so finding Telinu should not be very difficult.
For this quest you're supposed to go to the Eirulan Great Hall and pick up the Tome of Smithing for the recipe that Telinu needs. However, since you're reading a guide you can just give Telinu the correct answer instead of having to go collect the book.
Answer #3 is the correct one; Use 5 squares of leather, 3 pots of boiling wax, 12 stoneshroom discs, and 2 baskets of leaves. Coat the leather with wax, then fasten the leaves to the resulting armor. Give this to Apprentice Telinu and she'll successfully make you a piece of armor.