[单选题]
A microscope has an objective lens of f (vxj3 :-qq 0/hpoivf8xt3cva ocal length 1.4 mm and an eyep;vs/p*bg-( sm ph a7xui y)w9ziece of focal length 20 mm, adjusted for minimum eyestrain. A blood sample is placed 1.5 mm from the objective.im;pp/(u*7- 9y hgxaws )zbsv What is the overall magnification?
