Which of the following are the three main methods of placing concrete?

The three main methods of placing concrete are indeed pumping, chuting, and conveying by wheelbarrows or buggies. These methods are essential in the concrete finishing process, as they directly influence the efficiency and quality of the pour.

Pumping is commonly used for placing concrete at greater distances or heights and can be especially beneficial in large projects, allowing for faster and more controlled placement. Chuting involves pouring concrete from a height or into forms through a chute, which helps in directing the flow of concrete accurately. Conveying by wheelbarrows or buggies is often used for smaller projects or areas that are difficult to access, allowing for manual transport of concrete to the desired location.

Each of these methods has its unique characteristics and advantages, making them the standard practices in the industry for efficient concrete placement. The other choices, though they describe various actions, do not correctly represent the established methods used in concrete placement, making the correct answer clear.