Define incentive and explain the government's incentive for this regulation.

Incentives can be defined as mechanism by which we would like to increase the probability of a certain thing happening. Imagine you're incentivized to move to the outskirts of a city. A government can provide incentives in the form of subsidues where you would pay less for rent were you to move towards the outskirts of that city. 

Icould be wrong but i would say b.

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

producing or giving rise torelating to or engaged in the production of goods, crops, or other commodities.

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.