What is the process by which proteins stop migrating in an isoelectric focusing gel?

• A. Proteins stop migrating when they bind to a specific ligand in the gel.
• B. Proteins stop migrating when they reach a pH equal to their pI, resulting in a net charge of zero.
• C. Proteins stop migrating when they reach the end of the gel.
• D. Proteins stop migrating when they are fully denatured.

Answer: (B)