Nice question; I got it wrong - expected to choose between two (asynchronous and synchronous plus maybe some red herrings) when I read the question but then saw the three options and had to guess whether syncronous was called "high availability" or "high safety" and chose the wrong one.
Evgeny Garaev (3/26/2013)
Correction, Principal do not wait for commit transaction on the mirror. It waits for transaction being recorded in transaction log file on the mirror server. This is common misconception.
BOL disagrees with you:
A database mirroring session runs with either synchronous or asynchronous operation. Under asynchronous operation, the transactions commit without waiting for the mirror server to write the log to disk, which maximizes performance. Under synchronous operation, a transaction is committed on both partners, but at the cost of increased transaction latency.
and high safety mode uses synchronous operation.
Of course BOL is sometimes wrong, and I don't know whether it is right here or the author of this BOL page suffered from a "common misconception".