Two short bar magnets of length $1\text{cm}$ each have magnetic moments $1.20{\text{Am}}^2$ and $1.00{\text{Am}}^2$ respectively. They are placed on a horizontal table parallel to each other with their $N$ poles pointing towards the South. They have a common magnetic equator and are separated by a distance of $20.0\text{cm}$. The value of the resultant horizontal magnetic induction at the mid-point $O$ of the line joining their centres is close to ($B_H=3.6\times 10^{-5}{\text{Wb/m}}^2$):

1. A
   $2.56\times 10^{-4}{\text{Wb/m}}^2$
2. B
   $3.50\times 10^{-4}{\text{Wb/m}}^2$
3. C
   $5.80\times 10^{-4}{\text{Wb/m}}^2$
4. D
   $3.6\times 10^{-5}{\text{Wb/m}}^2$