A tangent is drawn at any point P(t) on the parabolay y² = 8x and on it is taken a point Q (a,ß) from which pair of tangents QA and QB are drawn to the circle x² + y² = 4. Using this information answer the following questions. The locus of the point of concurrency of the chord of contact AB of the circle x² + y² = 4x is:
a) y² - 2x = 0
b) y² - x² = 4
c) y² + 4x = 0
d) y² - 2x² = 4