A researcher is comparing the effectiveness of SDS-PAGE and 2D gel electrophoresis for protein separation. What is a major limitation of SDS-PAGE?

• A. SDS-PAGE provides less structural information than NMR.
• B. SDS-PAGE is slower than 2D gel electrophoresis.
• C. SDS-PAGE only separates proteins based on size, not charge or pH.
• D. SDS-PAGE requires antibodies for protein detection.

Answer: (C)