Electric Field of Dipole on Axial Line

Electric field decreases linearly

Electric field remains constant

Electric field decreases as inverse cube of distance (correct)

Electric field increases linearly

$E = \frac{1}{4\pi\epsilon_0} \frac{2p}{r^2}$

$E = \frac{1}{4\pi\epsilon_0} \frac{2p}{r^3}$ (correct)

$E = \frac{1}{4\pi\epsilon_0} \frac{p}{r}$

$E = \frac{1}{4\pi\epsilon_0} \frac{p}{r^2}$

Electric field becomes constant

Electric field becomes negligible

Electric field becomes zero (correct)

Electric field becomes infinite