Answer:
Initially
Step-by-step explanation:
The strategy to solve this problem is to plug in the choices to the sentence. The word "charmingly" wouldn't make sense as there is nothing in the sentence that gives off feelings of pleasantness or attractiveness.
"Critically" also doesn't make sense as nothing in the sentence connotes disapproval of any sort and, as we will see, there is a better choice available.
"Contrived" (meaning "deliberately created rather than arising naturally or spontaneously") doesn't work as nothing in the sentence tells us how long he took to make this decision.
"Previous" doesn't work because this word wouldn't be able to start of the sentence here, unlike the word "previously."
"Initially" is the best answer because at first he made a decision that he changed later on.