The equation of the circle drawn with the focus of the parabola <span class="math-inline">(x - 1)^{2} - 8y = 0</span> as its centre and touching the parabola at its vertex is :
<span class="math-inline">x^{2} + y^{2} - 4y = 0</span>
<span class="math-inline">x^{2} + y^{2} - 4y + 1 = 0</span>
<span class="math-inline">x^{2} + y^{2} - 2x - 4y = 0</span>
<span class="math-inline">x^{2} + y^{2} - 2x - 4y + 1 = 0</span>