Possible Clues:

• They incite responses
• Smoker's given up choked by a couple after way they provoked reaction
• Things that cause a response
• Reaction provokers
• Incentives limit us extraordinarily
• Things that rouse to activity
• Shots in the arm will limit us
• Incitements to action
• Spurs ground limits restricting United
• One chimney in Scotland — it's put up to provide inducements