Hey, i'm currently working on my economic homework and i have difficulties on one question:

Which of the following statements regarding price-based and quantity-based policies is correct?

Select one or more:

a.An advantage of quantity-based policies is that the implementation can be rapid and complete.

b.Banning lead in petrol is a price-based policy.

c.Price- and quantity-based policies can be more effective when used in conjunction, rather than one or the other.

d.A tax on carbon is a quantity-based policy.

I'm pretty sure answer A is correct and B and D are false.

However for the answer C i think its false but i'm not really 100% sure.

Am i wrong or right?

thanks for the help!