Final answer:
The electron cloud is the area around an atom's nucleus where electrons are most likely to be found, with electrons possessing more energy being found at higher energy levels within this cloud.
Step-by-step explanation:
The region where electrons are most likely to be found is referred to as the electron cloud. This is a probabilistic model representing the locations around an atom's nucleus where electrons are likely to be located. Electrons with the most energy would be found at higher energy levels, as they require more energy to be further away from the nucleus. Hence, referring to the provided options, the correct answer is (b) Electron cloud. The orbital is a specific region within this cloud where there is a high probability of finding an electron.