[单选题]
A microscope has an objectivi:+gyt2jweg8a7xi 1 pe lens ofi, b/.+duba rp6w k,du focal length 1.4 mm and an eyepiece of focal length 20 mm, adjusted for minimum eyestrain. A blood sample d +a,ud6k./ir,bwb up is placed 1.5 mm from the objective. What is the overall magnification?
