$\text{ Let }\mathrm{f}:\left[0,\frac{\pi }{2}\right]\to \mathrm{R}\text{ be a function defined by }\mathrm{f}\left(\mathrm{x}\right)=\max \left\{\sin x,\mathrm{cosx},\frac{3}{4}\right\}\text{ , then number of }$points where f(x) is non differentiable is

 

• A

  1

• B

  2

• C

  3

• D

  0