When slack of an activity is negative

it represents a situation where extra resources are available and the completion of project is not delayed
it represents that a programme falls behind schedule and additional resources are required to complete the project in time
the activity is critical and any delay in its performance will delay the completion of whole project
all of the above
✅ The correct answer is option B.

Which of the following are the guidelines for the construction of a network diagram?

Each activity is represented by one and only one arrow in the network.
Dangling must be avoided in a network diagram.
Dummy activity consumes no time or resource.
all of the above
✅ The correct answer is option D.