________ text flashes on and off as the document is viewed onscreen

Usually a _________ indicates to a program the end of a data structure.

a) backslash character b) forward slash character c) null reference d) null pointer

When the counter is_________ , the semaphore blocks other threads from accessing the semaphore until the semaphore has been released by another thread

a) 0. b) 1. c) negative. d) None of the above.