Final answer:
d. Three times the length of the ladder. The non-self-supporting ladder should be set up with the bottom one foot away from the wall for every four feet of the ladder's working length, effectively a quarter of the ladder's working length, though this is not listed among the provided options. In the context of lens magnification, a magnification of -1 results in an image that is inverted and of the same size as the object.
Step-by-step explanation:
A non-self-supporting ladder, commonly referred to as an extension ladder, should be set up at a certain horizontal distance from the wall for safety and stability. According to the 4 to 1 rule, which is a well-recognized safety standard, the bottom of the ladder should be placed one foot away from the wall for every four feet of working length (height) of the ladder. This translates to a setup where the horizontal distance to the wall is one-quarter of the working length of the ladder. Not provided among the options, the correct answer would be option a. Half the length of the ladder.
Regarding lenses, if a lens has a magnification of -1, the image formed would be inverted and of the same size as the object. Thus, if the object's height is unchanged but orientation is inverted, the answer is d. The image is inverted and is twice as tall as the object.