Most of the guests arrived . . . . . . . . buses. A. in B. from C. by D. with

The other options are not correct because:

• A. in is used to indicate a location or position. In this case, the guests did not arrive in buses, they arrived by buses.
• B. from is used to indicate a starting point or origin. In this case, the guests did not arrive from buses, they arrived by buses.
• D. with is used to indicate accompaniment or possession. In this case, the guests did not arrive with buses, they arrived by buses.