Final answer:
Deadlock 'may occur' in a system with 3 processes sharing 4 resources if each process holds one unit and waits for another, leading to a possible indefinite wait. However, it's not guaranteed to happen, as resource management can prevent it.
Step-by-step explanation:
The question is asking about the conditions that can lead to a deadlock in a system with multiple processes sharing resources. In this case, the system has 3 processes sharing 4 resources. Each process needs a maximum of 2 units. Deadlock occurs when each process holds one resource and waits for the second one, but because there are only 4 resources for 3 processes, each of which needs 2, they may end up waiting indefinitely if they've each secured one unit.
The correct answer to this situation is b) May occur. Deadlock 'may occur' because it's possible for all processes to hold one resource and wait for another, which isn’t available because it’s held by another process. However, if all processes request and are granted resources one at a time, they may avoid deadlock altogether, hence it is not certain that deadlock 'has to occur'.