Answer;
B.focus
The point beneath the surface where rock breaks and an earthquake is produced is known as the focus.
Step-by-step explanation;
When an earthquake occurs an area of the crust will move very suddenly and with a great release of energy. The point of the actual rock rupture is called the focus . The focus is usually found far beneath the surface. The point directly above the focus on the surface of the Earth is called the epicenter.
When the rocks move suddenly they will produce waves in the Earth's crust. These waves move out in all directions and can produce widespread damage on the Earth's surface.