Four point charges $\;+1 \mu C ,+1 \mu C,-1 \mu C-1 \mu C\;$ are placed at the four consecutive corners of a square of side 0.1m . What is the magnitude of electric field at E as shown in figure .

Question

$(a)\;144\times10^{4}\;\large\frac{(5 \sqrt{5}+1)}{\sqrt{5}}\qquad(b)\;72\times10^{4}\;\large\frac{(5 \sqrt{5}+1)}{\sqrt{5}}\qquad(c)\;36\times10^{4}\;\large\frac{(5 \sqrt{5}+1)}{\sqrt{5}}\qquad(d)\;None$