[单选题]
A convex lens has a f/uyr;su vn ,w/al19qik.g 3kb pmteg(32+3kj+ j xhczq.:wtwocal length $f$. An object is placed between infinity and $2f$ from the lens on its axis. The image formed is located
A. at $2f$.
B. between $f$ and $2f$.
C. at $f$.
D. between the lens and $f$.
