Final answer:
Arginine engages in positive ionic interactions due to its positively charged side chain and is commonly located on the outside of proteins and enzymes.
Step-by-step explanation:
Arginine is an amino acid that participates in ionic interactions because it has a positively charged side chain, which can interact with negatively charged side chains of other amino acids, such as aspartic acid or glutamic acid. These interactions are pivotal for the structure and function of proteins and enzymes. Specifically, arginine is typically found on the exterior of proteins, where it can interact with water and other polar substances in the cell environment. Considering all the details provided, the correct answer to the question is that arginine participates in positive ionic interactions and can be found on the outside of proteins/enzymes, making option (a) 'Positive; Outside' the correct choice.