2008 AMC 12A Problem 18

A triangle \triangle ABC with sides 5, 6, 7 is placed in the three-dimensional plane with one vertex on the positive x axis, one on the positive y axis, and one on the positive z axis. Let O be the origin. What is the volume of OABC?

\mathrm{(A)}\ \sqrt{85}\qquad\mathrm{(B)}\ \sqrt{90}\qquad\mathrm{(C)}\ \sqrt{95}\qquad\mathrm{(D)}\ 10\qquad\mathrm{(E)}\ \sqrt{105}

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.