The term "green light" indicates that the speaker
Like a good conversation, a good public speech is tuned to listeners. As you converse with people in social situations, you learn to monitor their reactions. If they look confused, you try to explain yourself more clearly. You may even give an example or tell a story. If they frown, you may replace an idea or present evidence that supports your views. If they smile or nod, you may feel you have the green light to develop your thoughts. If good conversations are interactive and audience centred, effective speeches are even more so.
Amay continue
Bmay stop
Cgive examples
Dmonitor the thoughts