What will be the magnitude of the electric field at point $O$ as shown in the figure? Each side of the figure has length $l$ and segments are perpendicular to each other.

• A
  $\frac{q}{4 \pi \varepsilon_{0} l^{2}}$
• B
  $\frac{1}{4 \pi \varepsilon_{0}} \frac{q}{2l^{2}}(2 \sqrt{2}-1)$
• C
  $\frac{1}{4 \pi \varepsilon_{0}} \frac{q}{l^{2}}$
• D
  $\frac{1}{4 \pi \varepsilon_{0}} \frac{2q}{2l^{2}}(\sqrt{2})$