$E,I,R,O$ denote respectively the sets of all equilateral, isosceles, right angled and obtuse angled triangles in a plane, then which of the following is not true

• A

  $R\cap E=\varphi ,R\cap I\ne \varphi$

• B

  $\begin{array}{r}E\cap O=\varphi ,O\cap I\ne \varphi \\ \end{array}$

• C

  $E\cap I=\varphi ,E\cap O\ne \varphi$

• D

  $E\cap I\ne \varphi ,E\subset I$