Option A is correct. notify() - wakes up a single thread that is waiting on this object's monitor.

Option B is wrong. wait() causes the current thread to wait until another thread invokes the 

notify() method or the notifyAll() method for this object.

Option C is wrong. Methods of the InputStream class block until input data is available, the end 

of the stream is detected, or an exception is thrown. Blocking means that a thread may stop until 

certain conditions are met.

Option D is wrong. sleep() - Causes the currently executing thread to sleep (temporarily cease 

execution) for a specified number of milliseconds. The thread does not lose ownership of any 

monitors.