Step 1: Rewrite the equation in standard form.
By completing the square and simplifying, we convert the given equation into the standard form of a hyperbola. The eccentricity \( e \) of a hyperbola is given by:
\[
e = \sqrt{1 + \frac{b^2}{a^2}}
\]
Substituting the values, we find the eccentricity to be \( \sqrt{2} \).
Thus, the correct answer is (2).