Which of the following is not a barrier to effective planning?

The correct answer is C. Flexibility in management.

A barrier to effective planning is something that makes it difficult to create or implement a plan. Difficulty of accurate premising, environmental changes, and time and cost factors are all barriers to effective planning.

Difficulty of accurate premising refers to the fact that it is often difficult to predict the future with accuracy. This can make it difficult to create a plan that is likely to be successful.

Environmental changes can also make it difficult to implement a plan. For example, if the economy changes, it may be necessary to change the plan in order to be successful.

Time and cost factors can also be barriers to effective planning. It may not be possible to implement a plan if it does not have the necessary resources.

Flexibility in management is not a barrier to effective planning. In fact, it can be helpful to have flexible management in order to be able to adapt to changes in the environment.

In conclusion, the correct answer is C. Flexibility in management.