Consider an element shown below. S is the source term. If gravitational force is the only force acting on this element. Which of these following is correct?

• A. Sx=mg, Sy=0, Sz=mg
• B. Sx=0, Sy=0, Sz=mg
• C. Sy=0, Sz=0, Sx=mg
• D. Sz=0, Sx=0, Sy=mg