For light diverging from a point source :
a) The wavefront is spherical
b) The intensity decreases in proportion to the distance squared
c) The wavefront is parabolic
d) The intensity at the wavefront does not depend on the distance

Light from point source emits in all around the source with same speed so forms a spherical surface of wavefront or spherical wavefront. $\mathrm{I}=\frac{\mathrm{P}}{4{\mathrm{\pi r}}^2}$As the intensity (I) always decreases as the reciprocal of square of distance.
r = radius of spherical wavefront at any time (r=vt)