Introduction:
The water-cement ratio is an important factor that determines the properties of concrete. It refers to the ratio of the weight of water to the weight of cement used in the concrete mix. A lower water-cement ratio means that less water is used for a given amount of cement, which has several effects on the properties of concrete.

Explanation:
The correct answer to this question is option 'D' - all of these. A lower water-cement ratio in concrete produces the following effects:

1. More density:
When the water-cement ratio is low, the amount of water available for the cement to hydrate is reduced. This results in a more compact and dense concrete mixture. The reduction in water content leads to a higher cement paste content, which fills the voids between the aggregates more effectively. As a result, the concrete becomes denser, increasing its overall density.

2. Small creep and shrinkage:
Creep and shrinkage are two common deformations that occur in concrete over time. Creep refers to the slow and continuing deformation of concrete under sustained load, while shrinkage refers to the reduction in volume of concrete due to the loss of moisture. A lower water-cement ratio helps in reducing both creep and shrinkage. This is because the reduced water content results in a lower overall moisture content in the concrete, leading to less drying shrinkage. Additionally, the reduced water-cement ratio also reduces the amount of pore water available for creep, resulting in smaller creep deformations.

3. More bond:
The bond between the cement paste and the aggregates is crucial for the strength and durability of concrete. A lower water-cement ratio improves the bond between the cement paste and aggregates. This is because the reduced water content allows for better hydration of cement particles, leading to a stronger and more cohesive cement paste. The improved bond between the cement paste and aggregates enhances the overall strength and durability of the concrete.

Conclusion:
In conclusion, a lower water-cement ratio in concrete produces more density, small creep and shrinkage, and more bond between the cement paste and aggregates. These effects are beneficial for achieving a stronger, more durable, and high-performance concrete.