B.C.

D

Long alignment, equal width and high level.

The length of the left view is 2, and the number below 2 is equal to the height of the top view.

In addition, this geometry is a regular triangular prism.

The bottom is a regular triangle.

∴ From Pythagorean Theorem, the length of the base is 4.

I can't read this picture.

Then the top view of the above picture is directly below the main view.

Then use a smooth curve to connect the point opposite to A with the point C that has just moved to the top view of the front view, and then connect BD, so that you can see the height of the top view and the length of the left view.