Final answer:
The point on a fault where an earthquake occurs is called the focus. Earthquakes happen due to the build-up and release of stress along plate boundaries, and the San Andreas Fault is a prime example of this process in action, guided by the theory of plate tectonics. The correct option is c.
Step-by-step explanation:
The point on a fault where an earthquake occurs is called the focus (option c). Earthquakes are a result of the motion along fault zones which is not smooth. The plates' creeping motion against each other builds up stresses within the Earth's crust.
When these stresses reach a breaking point, they are released as sudden, violent slippages along faults, generating earthquakes. The San Andreas Fault, a very active region in California, is an example where major slippages can produce extremely destructive earthquakes.
According to the theory of plate tectonics, the Earth's lithosphere is divided into multiple plates that are constantly moving. The boundaries where these plates interact are often sites of seismic activity.
When two plates slide past each other or collide, they can create faults or fault zones. The longer the interval between earthquakes, the greater the stress buildup, leading to more energy released during the actual earthquake event.
This relationship between plate movements and earthquake occurrences exemplifies the foundational concept of plate tectonics. The correct option is c.