What is an advantage of selecting an operating system that has a GPL license over one with a commercial license?

What is an advantage of selecting an operating system that has a GPL license over one with a commercial license?

• The GPL license-based operating system ensures that everyone can participate in the enhancement of the product.
• The GPL license-based operating system implements a structured development life cycle.
• The GPL license-based operating system prevents modification of the source code.
• The GPL license-based operating system provides structured support.

Exam with this question: CCNA Discovery 1: DHomeSB Final Exam