Introduction:
In structural engineering, lateral ties are used to provide lateral support to compression members such as columns. These ties help in preventing the buckling or lateral deformation of the column due to the applied loads. The pitch of lateral ties refers to the spacing or distance between consecutive ties along the length of the column.

Explanation:
The correct answer to the given question is option 'D', which states that the pitch of lateral ties should be the least of the above distances. Let's understand this in detail:

a) The least lateral dimension of the compression members:
The lateral dimension of a column refers to its smallest dimension, which can be the width or depth depending on the cross-sectional shape of the column. The pitch of lateral ties should not be equal to the lateral dimension of the column because it does not provide sufficient lateral support. Therefore, option 'a' is not the correct answer.

b) 16 times the smallest diameter of the longitudinal reinforcement bar to be tied:
This option suggests that the pitch of lateral ties should be 16 times the smallest diameter of the longitudinal reinforcement bar to be tied. However, this is not a universally accepted rule and may vary depending on the design codes and specifications followed. Therefore, option 'b' is not the correct answer.

c) 300 mm:
Option 'c' suggests that the pitch of lateral ties should be a fixed value of 300 mm. However, this value is not based on any specific design requirements and may not be appropriate for all columns. Therefore, option 'c' is not the correct answer.

d) Least of the above distances:
The correct answer to the given question is option 'd', which states that the pitch of lateral ties should be the least of the above distances. This means that the pitch should be determined based on the most restrictive requirement among the lateral dimension of the column, the diameter of the longitudinal reinforcement, and any other relevant design considerations. By choosing the least of these distances, we ensure that the lateral ties provide adequate lateral support to the column while minimizing the risk of buckling or lateral deformation.

Conclusion:
In conclusion, the pitch of lateral ties in a column should be the least of the distances mentioned in the options. This ensures that the column receives sufficient lateral support while considering the relevant design requirements. It is important to follow the design codes and specifications to determine the appropriate pitch of lateral ties for different columns.