When setting up an extension ladder against a wall, what is the generally recommended safe angle for optimal stability and safety?

✓ Correct Answer: Option C

The recommended safe angle for an extension ladder is often cited as the '4 to 1 rule': for every 4 feet of height the ladder reaches up the wall, the base should be 1 foot away from the wall. This creates an approximate 75-degree angle, providing good stability without being too steep (risk of tipping backward) or too shallow (risk of slipping at the base).