For drainage pipes in buildings the test applied before putting them to use, is A. Water test B. Smoke test C. Straightness test D. All the above

The correct answer is D. All the above.

Drainage pipes in buildings are tested before putting them to use to ensure that they are watertight and can withstand the weight of the building. The three main tests are:

• Water test: This test involves filling the pipe with water and checking for leaks.
• Smoke test: This test involves filling the pipe with smoke and checking for leaks.
• Straightness test: This test involves checking that the pipe is straight and does not have any kinks or bends.

All three tests are important to ensure the safety of the building and its occupants.