Three forces F₁, F₂, and F₃ together keep a body in equilibrium. If F₁ is equal to 3 Newton along the positive x-axis, F₂ is equal to 4 Newton along the positive y-axis, then the third force F₃ is:
A) 5 Newton at 45° to the positive x-axis
B) 5 Newton at 45° to the positive y-axis
C) 5 Newton along the negative x-axis
D) 5 Newton along the negative y-axis