Demand for organic foods has increased dramatically as Americans become aware of the effects of pesticides and other harmful chemicals in food. This exemplifies which force for change outside the organization?
1. Market changes
2. Technological advances
3. Supplier practices
4. Demographic characteristics

Atennis club charges a monthly membership fee of $150 and charges it members $10 per hour to use a court. there's also $500 fee to become a member. stella joined the tennis club last spring, and she has been a member for 5 months. she has been playing 10 hours of tennis each month. stella values an hour of her time at $20. during a boring afternoon meeting, stella thinks about reserving a court to work on her serve for an hour tonight. what's stella's opportunity cost of working on her serve for an hour?