The correct option is D Drawing an ace from a pack of 52 cards
A trial with a clearly defined outcome is an event.
Rolling a die has the outcomes as 1,2,3,4,5 and 6, and they are clearly defined. Hence, rolling a die is an event.
Tossing a coin has the outcomes as head and tail, and they are clearly defined. Hence, tossing a coin is an event.
Head and tail are the outcomes obtained when we toss a coin. Hence, head and tail are not an event.
Drawing an ace from a pack of 52 cards has the outcome as either it would be an ace or some other card, and they are clearly defined. Hence, drawing an ace from a pack of 52 cards is an event.
Therefore, option (a.), (b.) and (d.) are the correct answers.