Two point charges $1C$ and $-1C$ are placed $5mm$ away from each other forming a dipole. What will be the field intensity at a point $15cm$ away from the dipole on its axis?

a$)1\mathrm{.}66{10}^9\frac{N}{C}$

b$)2\mathrm{.}67{10}^{10}\frac{N}{C}$

c$)3{10}^{18}\frac{N}{C}$

d$)1\mathrm{.}4{10}^{16}\frac{N}{C}$