Here's why:
* "Who" is the subject of the verb "be trusted". Since the subject is performing the action, we use "who".
* "Whom" is the object of a verb or preposition. It's used when someone is receiving the action.
Let's break it down:
* "You are the one": This is the main clause.
* "who can be trusted": This is a relative clause modifying "one".
* "Can be trusted": This is a passive voice construction, meaning the person is being trusted (receiving the action).
Therefore, "who" is the correct pronoun to use in this sentence.