A barometer tube, containing mercury, is lowered in a vessel containing mercury until only 50 cm of the tube is above the level of mercury in the vessel. If the atmospheric pressure is 75 cm of mercury, what is the pressure at the top of the tube?
(A) 33.3 kPa
(B) 66.7 kPa
(C) 3.33 MPa
(D) 6.67 MPa