The correction for sag is A. always additive B. always subtractive C. always zero D. sometimes additive and sometimes subtractive

The correct answer is: D. sometimes additive and sometimes subtractive.

The correction for sag is the amount that a cable or wire will sag under its own weight. The amount of sag will depend on the length of the cable, the weight of the cable, and the material that the cable is made of.

In general, the correction for sag is added to the length of the cable when calculating the total length of the cable. However, there are some cases where the correction for sag is subtracted from the length of the cable. This is typically done when the cable is being used in a tensioned system, such as a suspension bridge.

The correction for sag is always taken into account when calculating the length of a cable. The amount of sag will vary depending on the specific application, but it is always important to take it into account.

Here are some additional details about each option:

• Option A: The correction for sag is always additive. This is not always the case, as the correction for sag can be either additive or subtractive, depending on the specific application.
• Option B: The correction for sag is always subtractive. This is also not always the case, as the correction for sag can be either additive or subtractive, depending on the specific application.
• Option C: The correction for sag is always zero. This is not the case, as the correction for sag will always be some value greater than or equal to zero.
• Option D: The correction for sag is sometimes additive and sometimes subtractive. This is the correct answer, as the correction for sag can be either additive or subtractive, depending on the specific application.