Per CA MUTCD Section 6F.64, what is the minimum height requirement for traffic cones used on freeways and high-speed highways?

1. 18 inches minimum height for all daytime operations.
2. 24 inches minimum height for all urban street operations.
3. 48 inches minimum height for all freeway shoulder operations and median closures.
4. 28 inches minimum height for high-speed roadways and nighttime use.