Final answer:
The correct answer to the student's question on what type of adapter is sometimes used to change the alignment of a concrete pressure pipeline is A) Flexible. Flexible adapters allow for alignment adjustments and accommodate movements in the pipeline.
Step-by-step explanation:
A flexible adapter is sometimes used to change the alignment of a concrete pressure pipeline. Flexible adapters, also known as couplings or joints, are employed to connect two pipes that may not be perfectly aligned or may need to accommodate movements or vibrations.
These adapters provide an essential function in pipelines, particularly in areas that are prone to ground movement or where the pipeline needs to navigate around obstacles. By being flexible, they allow for slight deviations in angle or direction without causing stress or damage to the pipes. Rigid connections do not offer this level of movement and can cause the pipes to break if they are forced to bend.
Therefore, the correct answer is A) Flexible.