A file that keeps track of the pictures, videos, and other files you have imported is called a(n):

a producer/consumer relationship, when a consumer finds the buffer empty or finds that the previous data has already been read, the consumer should call __________.

a. lock b. signal c. sleep d. await.

To connect multiple USB devices to a single USB port, a ____ can be used.

A. USB hub B. module C. USB bus D. connector