To prove that quadrilateral STUV is a parallelogram, the following conditions should be met:
- A parallelogram is defined as a quadrilateral with opposite sides that are equal in length.
From the choices provided, the most relevant condition that reflects the properties of a parallelogram is:
C. ST = UV and TU = SV.
This choice directly states that the opposite sides of the quadrilateral are equal, which confirms that STUV is indeed a parallelogram.
Thus, the correct answer to prove that STUV is a parallelogram is C.