[单选题]
A microscope has an objective lens of focal length 1.4 mm and an eye t i( 4vriiqhj(o7j2o5piece+ gp8k r ds/xeqg:se33 of focal length 20 mm, adjukq 8e+gr sg/d:psx3e3sted for minimum eyestrain. A blood sample is placed 1.5 mm from the objective. What is the overall magnification?
