The correct answer is option 'B': shrinkage deflection.

Explanation:
In reinforced concrete sections, the top and bottom reinforcement are designed to resist different types of forces and deformations. The top reinforcement is primarily responsible for resisting tension forces, while the bottom reinforcement is used to resist compression forces. The unequal distribution of reinforcement can lead to various types of deflections in the long term.

Shrinkage Deflection:
Shrinkage deflection occurs due to the shrinkage of the concrete as it dries and loses moisture over time. This shrinkage causes the concrete to contract, resulting in a reduction in its volume. When there is unequal top and bottom reinforcement, the shrinkage of the concrete is not uniform throughout the section. This non-uniform shrinkage leads to a difference in the deformations between the top and bottom of the section.

Effects of Unequal Reinforcement:
When the top reinforcement is significantly greater than the bottom reinforcement, the top of the section experiences more restraint during shrinkage. This causes the top of the section to undergo greater deformation compared to the bottom. As a result, the section may exhibit upward deflection at the top and downward deflection at the bottom.

Consequences:
The shrinkage deflection in the section can result in several practical consequences, including:

- Uneven cracking: The differential shrinkage can cause cracking in the concrete, especially at the top where the tensile stresses are higher. These cracks can compromise the structural integrity and aesthetics of the concrete element.

- Increased long-term deflection: The non-uniform shrinkage can contribute to long-term deflections in the section. This can affect the overall stability and performance of the structure.

- Serviceability issues: The differential deflection can lead to unevenness in the floor or other concrete elements, causing discomfort for occupants and affecting the functionality of the structure.

- Durability concerns: The cracks formed due to shrinkage deflection can provide pathways for moisture and other harmful agents to penetrate the concrete, potentially leading to corrosion of the reinforcement and reduced durability.

Therefore, it is crucial to ensure a balanced distribution of reinforcement in reinforced concrete sections to minimize shrinkage deflection and its associated consequences. Proper detailing and design considerations should be followed to achieve a uniform distribution of reinforcement throughout the section.