Final answer:
An integral membrane protein must be amphipathic with at least one hydrophobic region to allow it to integrate into the hydrophobic core of the cell membrane, with hydrophilic portions protruding to interact with the cell's internal or external aqueous environment.
Step-by-step explanation:
In order for a protein to be an integral membrane protein, it would have to be C) amphipathic, with at least one hydrophobic region. Integral proteins, or integrins, integrate completely into the membrane structure, and their hydrophobic membrane-spanning regions interact with the hydrophobic region of the phospholipid bilayer. These proteins have hydrophilic regions that protrude from the membrane to interact with aqueous environments like the cytosol or extracellular fluid. Meanwhile, their hydrophobic regions anchor the protein within the hydrophobic core of the phospholipid bilayer, allowing them to function as transporters, channels, or receptors within the cell membrane.