Answer:
The correct answer is - option A.
Explanation:
Among all of the given options the best character of the bacterial cell is the size of the cell which ranges in between 0.5 to 2 microns. The best evidence for the presence of bacterial cell is the smaller size of the cells.
Rest of the characters provided in the options does not matches with the characteristics of bacterial cells and not related to the bacteria.
Thus, the correct answer is option A.