For a $\Delta ABC$ it is given that : $\cos A+\cos B+\cos C=\large\frac{3}{2}$.What type of triangle is $ABC$?

Question

$\begin{array}{1 1}(a)\;Isosceles \;triangle&(b)\;Right\;angled\;triangle\\(c)\;equilateral\;triangle&(d)\;None\;of\;these\end{array}$