what is best mega piexil size of digital cameras for thaking picture to the images with best tissue resolution

Answer 1

More megapixels is always better. If you have more megapixels, you can make bigger prints.
3 megapixels enough for normal size pictures.
6 megapixels is better for full-page prints.
10 megapixels is good for small posters.
But the quality of the lens is even more important. With a bad lens, you will always get bad pictures. With a bad lens and 10-megapixels, you will get bad pictures that are really big!