In the transtheoretical model of behavior change, which stage indicates the period during which a person has modified the behavior in an observable way?

Answer: Action Stage

Explanation:The transtheoretical model of behavior change also known as stages of change is assesses an individual's readiness to act on a new healthier behavior and provides strategies or processes of change to guide the individual.

There are 6 different stages of change and they are:

Stage 1: Precontemplation: People at this stage have no intention to start a change in healthier behaviour in the nearest future.

Stage 2: Contemplation: People at this stage have the intention to start a change in healthier behaviour at a near date.

Stage 3: Preparation: People at this stage are ready to take action as soon as possible

Stage 4: Action: People at this stage are currently working on their behavioural change and intend to continue.

Stage 5: Maintenance: People at this stage have changed their behaviour in the past few months and are aware of situations that may pull them back.

Stage 6: Relapse: Are people who have overcome their unhealthy behaviours but goes back to those unhealthy behaviours after a while.