A box is at rest on a frictionless surface. Three forces are exerted on the box such that box remains at rest. One is a force of 100 N towards the east. Another is a force of 100 N towards the north. What is the third force?

(A) Zero N towards the Northeast.
(B) 141.42 N towards the Northeast.
(C) 141.42 N towards the Southwest.
(D) None of the above