Choose the correct form of adverb for the given sentence:
They planned to meet _________ before the agreement was made.

- previously - at a previous or earlier time; before.
- casually - in a relaxed and informal way.
- formerly - in the past; in earlier times.
- formally - in accordance with convention or etiquette.
- The word 'agreement' in the latter part of the given sentence suggests that the two sides met officially, the adverb 'formallly' will be the most appropriate choice.
- Correct Sentence: They planned to meet formally before the agreement was made.