To find the original location of the vertex Q before the transformation of the rectangle based on the rule \( R_0, 90^\circ \), we need to understand that a rotation of \( 90^\circ \) counterclockwise around the origin will transform a point \( (x, y) \) into \( (-y, x) \).
Given the new coordinates of the point Q' after rotation, which is \( Q'(-3, 4) \), we can apply the inverse transformation to find the original location of vertex Q.
The inverse transformation of \( (-y, x) \) is \( (y, -x) \).
Substituting the coordinates of Q':
- \( y = 4 \)
- \( x = -3 \)
Applying the inverse transformation: \[ Q = (y, -x) = (4, -(-3)) = (4, 3) \]
Thus, the location of Q before the transformation is \( (4, 3) \).
Among the provided options, the correct answer is: (4, 3).