Introduction:
The fineness of cement refers to the particle size distribution of the cement particles. It is an important factor that affects the properties of cement and its performance in concrete. A finer cement has a larger surface area, which can influence the rate of strength development and other properties of concrete.

Explanation:
The correct answer is option B, which states that an increase in the fineness of cement increases the rate of strength development and reduces the rate of deterioration. This can be explained as follows:

1. Rate of strength development:
- When cement particles are finer, they have a larger surface area, which allows for better hydration and reaction with water. This leads to a faster rate of strength development in the early stages of concrete curing.
- The finer particles provide more nucleation sites for the formation of hydration products, resulting in a higher rate of strength gain.
- Additionally, the increased surface area allows for more efficient chemical reactions, leading to a more complete and rapid hydration process.

2. Rate of deterioration:
- A finer cement generally has a lower permeability, which means it is less prone to the ingress of harmful substances such as water, chemicals, and gases.
- The reduced permeability helps to protect the concrete from deterioration caused by factors such as freeze-thaw cycles, chemical attack, and carbonation.
- Finer cement also results in a denser concrete matrix, which enhances its resistance to various forms of deterioration and extends its service life.

3. Other factors:
- While an increase in fineness can improve the rate of strength development and reduce the rate of deterioration, it may also have some negative effects.
- Finer cement tends to have a higher water demand, which can lead to increased bleeding (the separation of water from the cement paste).
- Higher bleeding can result in surface defects and reduced durability of concrete.
- Additionally, the increased surface area of finer cement particles can lead to higher shrinkage in concrete, which may cause cracking and reduce the long-term durability of the structure.

Conclusion:
In conclusion, an increase in the fineness of cement has several effects on the properties of concrete. It primarily increases the rate of strength development and reduces the rate of deterioration. However, it may also lead to higher bleeding and shrinkage, which can negatively impact the durability of concrete. Therefore, it is important to carefully balance the fineness of cement to achieve the desired properties in concrete.