CMAKE Generation issue in Ubuntu

I just wanted to run CMAKE so that i can build a C++ project to generate the .so files of VTK . I am using
CMAKE 3.20.2 with Unix MakeFiles
G++ 9.3
and I have tried vtx 9.0 and 8.2

for 9.0 i have the following error:
Could NOT find X11 (missing: Xt)
CMake Error at CMake/vtkModule.cmake:4140 (message):
Could not find the X11 external dependency.
Call Stack (most recent call first):
Rendering/OpenGL2/CMakeLists.txt:334 (vtk_module_find_package)

and i have tried ```
sudo apt-get install libx11-dev

to resolve but without any success