If a fair coin is tossed once, the probability of getting a HEAD is

1. For a fair coin, the sample space is $S = \{H, T\}$ with each outcome equally likely. 2. Probability of an event $E$ for equally-likely outcomes: $P(E) = \dfrac{|E|}{|S|}$. 3. Here $E = \{H\}$, $|E| = 1$, $|S| = 2$. So $P(E) = 1/2$. 4. Probabilities always lie in $[0, 1]$: option A (0) means impossible event; option C (1) means certain event. 5. Option D ($1/4$) would correspond to TWO coin tosses both being heads, not one. _Source: syllabus Mathematics, Ch 14, §14.2.2 (Probability of equally likely outcomes), p. 7._