Option 1 -> "by means of" indicates a method or instrument, which doesn't fit the context of describing terms.
Option 2 -> "agreeable to" means acceptable or satisfactory to someone, fitting perfectly with describing terms that both parties found acceptable.
Option 3 -> "in course of" means during or in the process of, which is grammatically incorrect in this context.
Option 4 -> "in order to" expresses purpose and requires a verb to follow, making it unsuitable here.
Hence, Option 2: agreeable to -> The phrase "agreeable to both the parties" correctly conveys that the terms were acceptable and satisfactory to both sides, which naturally led to a smooth transaction -> correct