A 16-foot extension ladder leaning against a structure must have a base distance of about?

For a 16-foot extension ladder, the recommended base distance from the structure is based on the general safety guideline of a 4-to-1 ratio. This means for every four feet of ladder height, the base should be positioned one foot away from the wall.

In this case, a 16-foot ladder would require the base to be placed at a distance of about 4 feet from the structure. This positioning ensures stability and safety, reducing the risk of the ladder slipping or tipping over when a person is climbing or working on it. Proper ladder placement is crucial to prevent accidents and ensure the technician's safety while performing tasks at height.

The other options suggest distances that do not adhere to the 4-to-1 rule, resulting in potentially unsafe angles of the ladder.