Step 1: Using the Poisson distribution.
The Poisson distribution is given by \( P(X = k) = \frac{\lambda^k e^{-\lambda}}{k!} \). Using the given condition, solve for \( \lambda \) and calculate \( E(X) = \lambda \).
Step 2: Conclusion.
Thus, the correct answer is option (B).
Final Answer:
\[
\boxed{\text{(B) } 1.5}
\]