The most appropriate preposition to use in filling the blank is: to.
In English language, a preposition is one of the parts of speech and it can be defined as a word that shows or illustrates the relationship between a pronoun or noun and other words in a sentence. Some examples of a preposition used in various literary works in English language are; up, below, after, by, against, for, over, at, to, etc.
The main purpose of a preposition is to introduce an object by using (of, upon), indicate a timeframe by using (from, by, over), show direction by using (to, across, along), location or place (at, up, after, below) and to illustrate the spatial or sequential relationship between two or more things, people, place, etc.
In this context, allow to connotes permission and as such should be used when someone or something is permitted (allowed) to do a thing.
On the other hand, <u>allow for</u> should be used in instances where there are options or when considering possibilities i.e an event that will or might happen in the future.
<em>In conclusion, a government issued passport allows you to (permit) travel abroad while other documents from other institution allows for (possibilities) travel abroad.</em>
