Step 1: Consider a chord of the hyperbola
The equation of the hyperbola is:
\(
x^2 - y^2 = a^2.
\)
Let \( (x_1, y_1) \) and \( (x_2, y_2) \) be the endpoints of a chord. The midpoint of the chord is:
\(
\left( \frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2} \right).
\)
Step 2: Condition that the chord touches the given parabola
The equation of the given parabola is:
\(
y^2 = 4ax.
\)
The chords of the hyperbola that touch this parabola satisfy a special midpoint locus equation, which has been derived using midpoint properties and conic section relationships.
Step 3: The required locus equation
The locus of the midpoint of such chords is given by:
\(
x(y^2 - x^2) = ay^2.
\)
Thus, the correct answer is option (A).