So if we choose plan p then we have to forgo plan Q as they are mutually exclusive.

a) is the best option.

Having a look at the other possible options:

Mutually exclusive events are the ones when they cannot happen at same time, that is, there is no outcomes common in these events. For example: getting a head or a tail when a coin is tossed. On tossing a coin, we can never get head or tail together, so these two events are mutually exclusive.

Mutually inclusive events are the ones in which there are some common outcomes in between the given events. Like getting an odd number or getting a prime number when we throw a dice. In these two events there are common outcomes {3, 5} repeating in both the events. So these two events are mutually inclusive events.

a) correct

b) by the definition of mutually inclusive events forget is not right

c)Mutually exclusive: any two of a set of given events are disjoint; i.e. a point of your probability space is in at most one event. Mutually exhaustive: your set of events covers the whole probability space - every point of your probability space is in at least one event. So it doesnot mean that we have to accept plan Q.. so this is also not correct.