Consider the following two events and select the correct option.

Event A: Meghna is going to get a prize and a medal today.

Event B: Meghna won the race competition today.

In many contexts, winning a race (Event B) is the reason a person is awarded a prize and a medal (Event A). That is, winning the competition is the cause, and the prize/medal is the effect.

So, Event B is the principal and immediate cause and Event A is its effect.

Thus, correct option is (b).