power 4dLatest Live 4D Results for Magnum 4D, Sports Toto 4D, Damacai 1+3D, Diriwan 88 Lotto 4D, Sarawak Special Cash Sweep 4D, STC 4D, Singapore Pools 4D + TotoTranscript. Question 39 If the power of a lens is − 4.0 D, then it means that the lens is a (A) concave lens of focal length −50 m (B) convex lens of focal length +50 cm