Answer:
C). The structures in the cell work together to perform its life functions.
Step-by-step explanation:
Unicellular organisms are characterized as organisms that are able to perform all the life functions through a single-cell. The third statement correctly elaborates how 'single-celled organisms carry out these life functions by cooperatively employing the structures lying inside the cell.' The first option is incorrect as it talks about multi-cells which doesn't even exist in unicellular organisms. While the second option is wrong because there are no tissues formed of single-cell. The last option is incorrect as the specialized cells perform different life functions in multi-cellular organisms. Thus, option C is the correct answer.