Option 1 -> Means to keep someone at a distance or prevent them from approaching; doesn't relate to causing annoyance.
Option 2 -> Means to annoy or irritate someone, typically through one's words or behavior; perfectly matches causing irritation through thoughtless remarks.
Option 3 -> Means to have a direct confrontation to resolve a conflict; doesn't fit the context of causing annoyance.
Option 4 -> Means to be in ongoing disagreement or conflict with someone; suggests mutual conflict rather than one person irritating others.
Hence, Option 2: rub someone up the wrong way -> This idiom precisely captures the situation where someone's casual and thoughtless remarks unintentionally annoyed and irritated their colleagues, as "rubbing someone up the wrong way" means to irritate or annoy someone through one's behavior or words -> correct