An under-reinforced section means A. Steel is provided at the underside only B. Steel provided is insufficient C. Steel provided on one face only D. Steel will yield first

Steel is provided at the underside only
Steel provided is insufficient
Steel provided on one face only
Steel will yield first

The correct answer is: B. Steel provided is insufficient.

An under-reinforced section is a concrete beam that has insufficient steel reinforcement to carry the applied loads. This can lead to the concrete cracking and failing prematurely.

Option A is incorrect because steel can be provided at both the top and bottom of a concrete beam.

Option C is incorrect because steel can be provided on both faces of a concrete beam.

Option D is incorrect because steel will not always yield first in an under-reinforced section. In some cases, the concrete may crack and fail before the steel yields.