The correct option is
B Biconvex and cannot be moved forward.
- At rest, the lens in the normal eye focuses images of distant objects on the retina.
- It acts in much the same way as a biconvex optical glass lens, however, it cannot be moved forward.
- Thus, the refractive power of the lens is a function of the curvature of the lens surfaces, as well as the refractive index of the cell mass.
- The closely packed, highly ordered array of lens cells is essential for optical quality, and even small defects in lens fiber cell anatomy can cause detectable spherical aberration.
So, the answer is - 'Biconvex and cannot be moved forward'.