The correct answer is A. Segregation.
Segregation is the separation of the different components of concrete, such as the aggregate, cement, and water, from each other. This can happen during mixing, placing, or finishing of the concrete. Segregation can lead to a number of problems, such as weak concrete, honeycombing, and cracking.
Compaction is the process of reducing the voids in concrete by applying pressure. This is done by vibrating or tamping the concrete. Compaction is important to ensure that the concrete is dense and has good strength.
Shrinkage is the reduction in volume of concrete that occurs after it has been placed and finished. Shrinkage can be caused by a number of factors, such as the loss of water from the concrete, the setting of the cement, and the temperature changes. Shrinkage can lead to cracking of the concrete.
Bulking is the increase in volume of concrete that occurs when it is mixed. This is due to the absorption of water by the aggregate. Bulking can lead to problems with the placement and finishing of the concrete.
I hope this helps!