You are working with different tissues in lab, unfortunately you forgot to label them and your friend wants to borrow your slide containing liver tissue. based on your knowledge of the liver and these descriptions of different slides which is most likely to be liver tissue?

A slide with densely packed cells and canals for blood flow.

Mitochondria produce atp, a high energy compound. atp is used for all sorts of enzyme-mediated reactions, such as making proteins/nucleotides/etc, certain compounds cross the cell membrane, muscles move, etc.  without this source of energy, a cell will die. it will not be able to repair itself, defend against pathogens, etc.