What characterizes limited-access highways in Oklahoma?

• They have many stop signs and traffic signals.
• They often have steep hills and sharp curves.
• They provide safe and uninterrupted travel at higher speeds.
  Explanation:

  "Oklahoma has many miles of limited-access highways designed for safe, uninterrupted travel at higher speeds. There are no stop signs, traffic signals, or railroad crossings. Freeways, toll roads, throughways, turnpikes, and expressways usually have no steep hills or sharp curves that limit your view of the road ahead. "
• They frequently intersect with railroad crossings.