For a thin concave lens of focal length 10cm, an object is placed 5cm in front of the lens. What is the magnification produced by the lens?
a) −2.0 (image inverted, magnified)
b) +2.0 (image erect, magnified)
c) +0.67 (image erect, diminished)
d) −0.67 (image inverted, diminished)