Check lines (or proof lines) in Chain Surveying, are essentially required A. To plot the chain lines B. To plot the offsets C. To indicate the accuracy of the survey work D. To increase the out-turn

The correct answer is C. To indicate the accuracy of the survey work.

Check lines are used to check the accuracy of the survey work by providing a second set of measurements that can be compared to the original measurements. If the two sets of measurements are not the same, then there is an error in the survey work and it needs to be corrected.

Option A is incorrect because check lines are not used to plot the chain lines. The chain lines are the lines that are actually measured in a chain survey.

Option B is incorrect because check lines are not used to plot the offsets. The offsets are the distances from the chain lines to the objects being surveyed.

Option D is incorrect because check lines do not increase the out-turn. The out-turn is the amount of work that is done in a survey. Check lines do not increase the amount of work that is done, but they do help to ensure that the work is done accurately.