Factors of $\;(x^{2} + \large\frac{x}{6}- \large\frac{1}{6})\;$ are

Question

$(a)\;\large\frac{1}{6} (2x+1)(3x+1)\qquad(b)\;\large\frac{1}{6} (2x+1)(3x-1)\qquad(c)\;\large\frac{1}{6} (2x-1)(3x-1)\qquad(d)\;\large\frac{1}{6} (2x-1)(3x+1)$