For a Poisson distribution, the expected value E(X) = λ = 0.25. The probability mass function for a Poisson random variable is:

P(X = k) = (e^{-λ} * λ^k) / k!

For k = 1: P(X = 1) = (e^{-0.25} * 0.25^1) / 1! P(X = 1) = e^{-0.25} * 0.25

Calculating e^{-0.25} ≈ 0.7788 Then: 0.7788 * 0.25 ≈ 0.1947 ≈ 0.19

Therefore, the correct answer is 0.19.