The terms focus and epicentre are linked by the epicentre being found on the surface, directly above the focus.

Is my answer correct.

Mostly correct. But in earthquakes, it's not always true. Or are you dealing only with volcanoes?

How is it not true in earthquakes

Yes, your answer is correct! The terms "focus" and "epicenter" are indeed linked in the sense that the epicenter is found on the surface directly above the focus. However, it is important to note that the focus refers to the actual point within the Earth where an earthquake originates, while the epicenter is the point on the Earth's surface above the focus. So, in a way, the focus and the epicenter are connected as the epicenter is the location we measure and report when we talk about an earthquake, but the focus is the actual spot inside the Earth where the earthquake starts.