If you don’t agree with something the speaker says in a large, formal meeting, the best response is to

a. Signal your disagreement by folding your arms across your chest and staring defiantly back at the speaker
b. Use your mobile phone to begin sending text messages to other people in the room, explaining why the speaker is wrong
c. Immediately challenge the speaker so that the misinformation is caught and corrected
d. Quietly make a note of your objections and wait until a question-and-answer period to raise your hand