Shrinkage of concrete depends upon i) humidity of atmosphere ii) passage of time iii) stress The correct answer is A. (i) and (ii) B. (ii) and (iii) C. Only (iii) D. All (i), (ii) and (iii)

The correct answer is D. All (i), (ii) and (iii).

Shrinkage of concrete is a complex phenomenon that is influenced by a number of factors, including the following:

• Humidity of atmosphere: Concrete is a porous material, and water is one of the main components of concrete. As concrete dries, it shrinks. The rate of shrinkage is affected by the relative humidity of the atmosphere. In a dry atmosphere, concrete will shrink more than in a humid atmosphere.
• Passage of time: Concrete continues to shrink for many years after it is placed. The rate of shrinkage decreases with time, but it never completely stops.
• Stress: Concrete is a strong material, but it can be stressed by loads, such as the weight of a building or a bridge. Stress can cause concrete to shrink.

The following are some additional details about each of these factors:

• Humidity of atmosphere: The relative humidity of the atmosphere is the amount of water vapor in the air relative to the maximum amount of water vapor that the air can hold at a given temperature. When the relative humidity is low, the air can hold more water vapor, and concrete will shrink more. When the relative humidity is high, the air cannot hold as much water vapor, and concrete will shrink less.
• Passage of time: Concrete continues to shrink for many years after it is placed. This is because concrete is a porous material, and water is one of the main components of concrete. As concrete dries, it shrinks. The rate of shrinkage decreases with time, but it never completely stops.
• Stress: Concrete is a strong material, but it can be stressed by loads, such as the weight of a building or a bridge. Stress can cause concrete to shrink. This is because stress can cause the water in concrete to move, and this movement can cause the concrete to shrink.

In conclusion, the correct answer is D. All (i), (ii) and (iii). Shrinkage of concrete depends upon humidity of atmosphere, passage of time, and stress.