[单选题]
A microscope has an objective lens of fo96lj(*4zkwx(gfmuirwe q6w; cal length 1.4 mm pj( tj ;h)4hfing+/uzand an eyepiece of focal length 20 mm, adjusted for minimum eyestrain. A blood sample is placed 1.5 mm from the objepu(hi) fg z+;j/htj 4nctive. What is the overall magnification?
