Where marginal private cost equals marginal private benefit.

Where marginal private cost equals marginal social benefit

Where marginal social cost equals marginal private benefit

Where marginal social cost equals marginal social benefit

A regulation limiting how much CO2 a power station can emit per megawatt of electricity generated.

A tax on electricity

A tax on emissions of CO2

Giving power stations the property right to emit CO2, and relying on people affected to bribe them to cut back

A regulation limiting how much CO2 a power station can emit per megawatt of electricity generated

A tax on electricity

A tax on emissions of CO2

Giving power stations the property right to emit CO2, and relying on people affected to bribe them to cut back

When Wimbledon’s Centre Court has the legal maximum number of 15,000 spectators, watching a match there is non-rival because so many people are watching it

A tennis racket is non-rival, because one person can use it today while another can use it tomorrow

All motorways are excludable, because people could be charged tolls for using them

National Health Service hospitals are non-excludable, because patients are not charged for using them

Both 1 and 2

1 only

2 only

Neither 1 nor 2