What is a dummy activity?

A Smart Question indeed! Thanks.

I fully endorse answer given by You, Mr.  Mohammed Helal.

agree with expert answers above

A dummy activity is a simulated activity of sorts, one that is of a zero duration and is created for the sole purpose of demonstrating a specific relationship and path of action on the arrow diagramming method.

Dummy activities are a useful tool to implement when the specific logical relationship between two particular activities on the arrow diagramming method cannot specifically be linked or conceptualized through simple use of arrows going from one activity to another. In this case, the creation of a dummy activity, which serves essentially as a form of a placeholder, can provide exceedingly valuable.

Dummy activities should in no cases be allocated any duration of time in the planning and/or scheduling or project activities and components. When they are illustrated in a graphical format, dummy activities should be represented by the user of a dashed line with an arrow head on one end, and may in some cases be represented by a unique color.

Thanks

I think it is (A & C).

My opinion is that the right answer is:

D. all the above

I agree with colleagues

A & C

thanks for the invitation

Option D: Above All is the correct response.

A dummy activity is :

A : artificially introduced

C : does not consume time

Option D- is the most appropriate answer

I feel Option D is the correct option since all the first 3 are applicable in this activity.

Thanks for the invitation, I  agree with all answers