The statement that best describes the Mayan writing system is **b. the Mayan writing system was the most evolved in the Americas**. The Mayan writing system, known as hieroglyphics, was highly developed and complex compared to other writing systems in the Americas.
To clarify the other statements:
- **a. the Mayan writing system was more advanced than Eurasian cultures**: This is subjective and not universally accepted, as "advanced" can vary by context.
- **c. the Mayan writing system and all evidence of it was destroyed by the Spanish**: While many texts and monuments were destroyed, not all were lost, and some knowledge of the system survives.
- **d. the Mayan writing system is still widely used in Central America today**: The traditional script is not widely used today, though some Mayan languages continue to be spoken.
Therefore, option **b** is the most accurate.