During which stage of change in the transtheoretical model does an individual acknowledge that they have a problem, and they considering making a change within the next 6 months?

Contemplation

Explanation:

The transtheoretical model provides a model according to which a person changes their behavior

According to this theory there are 6 stages through which a person changes their habits.

Precontemplation: The person does not intend to take any action in the near future in this stage.Contemplation: The person understands that their behavior is problematic or begins to think so and decides whether it is good for them to change their habit or not.Preparation: The person plans to take steps towards changing their behavior after becoming completely aware that their behavior is negative.Action: The person is actively taking steps in order to change their behavior.Maintenance: In this stage the person tries to sustain their action which they have taken.Termination: The person has completely loses their habit they wanted to change and do not have the will to go back to their old ways.