Explanation/Reference:
F: A convert queue is a queue of locks that are waiting to be converted to particular mode, this is the process of changing a lock from one mode to another, even a NULL is a lock. A resource has a lock value block (LVB). The Global Resource Manager (GRM) keeps the lock information valid and correct across the cluster. Oracle 10g release 2 and beyond replaced some latch mechanisms with the mutex approach, claiming that they are faster and more efficient than traditional locking mechanisms.
Incorrect Answers:
B, D: Mutexes are objects that exist within the operating system to provide access to shared memory structures. They are similar to latches.
References: http://www.datadisk.co.uk/html_docs/rac/grd.htm