The cost associated with foregoing the opportunity to employ a resource in its best alternative use is called:

1. A sunk cost.
2. Total cost.
3. Opportunity cost.
4. The market price.

When the price of penicillin tablets increases by 10%, the drug company's revenue decrease by 6%. Its elasticity of demand (in absolute terms) must be:

1. Zero.
2. Greater than one.
3. Less than one.
4. Infinitely large.