A. 0.25

Workings:

1. For a coin toss: Probability of getting a tail = 1/2
2. For an unbiased die: Numbers greater than 3 are 4, 5, and 6 Probability of getting a number greater than 3 = 3/6 = 1/2
3. The probability of both events occurring together is the product of their individual probabilities: P(tail and number > 3) = P(tail) × P(number > 3) = 1/2 × 1/2 = 1/4 = 0.25

Therefore, the probability of obtaining a tail and a number greater than 3 when tossing a coin and an unbiased die together is 0.25.