The correct answer is option 'A', which states that the limit state of collapse deals with the strength and stability of the structure. Let's understand why this answer is correct in detail:

Strength and stability of the structure:
- The limit state of collapse refers to a state where the structure under consideration can no longer sustain the applied loads and results in a complete failure or collapse.
- It is an important design consideration to ensure that the structure has sufficient strength and stability to withstand the expected loads and forces that it will be subjected to during its lifetime.
- The strength of a structure refers to its ability to resist the applied loads without excessive deformation or failure. It is typically measured using parameters such as yield strength, ultimate strength, and factor of safety.
- Stability, on the other hand, refers to the ability of the structure to maintain its equilibrium and resist overturning, sliding, or excessive deformation under the applied loads.
- The limit state of collapse is concerned with analyzing and designing the structure to ensure that it does not reach a state where the applied loads exceed its strength or stability limits, leading to collapse.

Conditions such as deflection, cracking, and durability are not directly related to the limit state of collapse, as stated in options 'B', 'C', and 'D'. However, they are important considerations in the overall design of a structure. Let's briefly understand these concepts:

Conditions such as deflection:
- Deflection refers to the deformation or displacement of a structure under the applied loads. It is a measure of how much the structure bends or moves from its original position.
- Excessive deflection can affect the performance and functionality of the structure, leading to discomfort for occupants, damage to finishes or other components, or even structural failure in extreme cases.
- Deflection limits are typically specified in design codes to ensure that the structure remains within acceptable limits.

Conditions such as cracking:
- Cracking refers to the formation of cracks in the structure, which can occur due to various factors such as excessive loads, shrinkage, temperature changes, or poor construction practices.
- Cracks can affect the structural integrity of the building and may allow the ingress of moisture or other harmful agents, leading to deterioration and reduced durability.

Durability:
- Durability refers to the ability of the structure to withstand the effects of aging, weathering, and deterioration over its intended design life.
- It involves considerations such as material selection, protection against corrosion, resistance to environmental factors, and proper maintenance practices.
- Ensuring the durability of a structure is important to prevent premature failure or collapse.

In summary, while conditions such as deflection, cracking, and durability are important aspects of structural design, the limit state of collapse specifically deals with the strength and stability of the structure to prevent complete failure or collapse under the applied loads.