The risk coefficient k, depends on A. Mean probable design life of structures B. Basic wind speed C. Both (A) and (B) D. None of the above

The correct answer is: C. Both (A) and (B).

The risk coefficient $k$ is a factor that is used to calculate the probability of failure of a structure. It depends on the mean probable design life of the structure and the basic wind speed. The mean probable design life is the expected lifetime of the structure, and the basic wind speed is the maximum wind speed that is expected to occur at the site of the structure.

The risk coefficient is used to calculate the probability of failure of a structure by multiplying the basic wind speed by the mean probable design life and dividing by the product of the shape factor and the gust factor. The shape factor is a factor that depends on the shape of the structure, and the gust factor is a factor that depends on the variability of the wind speed.

The risk coefficient is an important factor in the design of structures that are exposed to wind loads. It is used to ensure that the structure is designed to withstand the expected wind loads without failing.

The following is a brief explanation of each option:

• Option A: Mean probable design life of structures. The mean probable design life is the expected lifetime of the structure. It is used to calculate the risk coefficient by multiplying it by the basic wind speed and dividing by the product of the shape factor and the gust factor.
• Option B: Basic wind speed. The basic wind speed is the maximum wind speed that is expected to occur at the site of the structure. It is used to calculate the risk coefficient by multiplying it by the mean probable design life and dividing by the product of the shape factor and the gust factor.
• Option C: Both (A) and (B). The risk coefficient depends on both the mean probable design life of structures and the basic wind speed. It is used to calculate the probability of failure of a structure by multiplying the basic wind speed by the mean probable design life and dividing by the product of the shape factor and the gust factor.
• Option D: None of the above. The risk coefficient does not depend on none of the above. It depends on both the mean probable design life of structures and the basic wind speed.