A point source of light S is placed on the axis of a lens of focal length 20cm at a distance 25cm from lense. A screen is placed normal to the axis of lens at a distance x from it (treat all rays as paraxial). Identify the true or false statements.
a. As x is increased from zero , intensity continuously decreases.
b. As x is increased from zero, intensity first increases then decreases.
c. Intensity at center of screen for `x =90 cm` and `x=110 cm` is same.

Options

A. As x is increased from zero, intensity continuously decreases
B. As x is increased from zero, intensity first increases and then decreases
C. Intensity at centre of screen for `x=90cm`and `x = 110cm` is same
D. radius of bright circle obtained on screen is equal to1cm for `x=200 cm`