[amp_mcq option1=”100 m” option2=”150 m” option3=”200 m” option4=”300 m” correct=”option3″]
The correct answer is: C. 200 m.
Ventilating shafts are provided to a sewer line at every 200 m to provide fresh air to the sewer line and to prevent the build-up of gases. The gases in a sewer line can be harmful to human health and can also cause explosions.
Option A is incorrect because 100 m is not a common distance between ventilating shafts. Option B is incorrect because 150 m is not a common distance between ventilating shafts. Option D is incorrect because 300 m is not a common distance between ventilating shafts.