Option C is correct. The start() method causes this thread to begin execution; the Java Virtual Machine calls the run method of this thread.
Option A is wrong. The run() method of a thread is like the main() method to an application. Starting the thread causes the object's run method to be called in that separately executing thread.
Option B is wrong. There is no construct() method in the Thread class.
Option D is wrong. There is no register() method in the Thread class.