Answer:
Undoubtedly
Step-by-step explanation:
The word 'For sure' could be explained to mean that something or a certain phenomenon will happen or take place. It's a phrase which shows a very high level of certainty. Word which are synonymous with the phrase include; Certainly, Surely, Definitely, Undoubtedly and so on. Of the words in the option given ; However, Somehow and For the most part all also showcase degree of certainty, however, They still exhibit a certain level of doubt and thus shows a lower degree of certainty than 'Undoubtedly', which in explicit term means 'without doubt'.