"extortion of private persons is commonly referred to as "

"Extortion of private persons is commonly referred to as blackmail."
The term blackmail denotes a criminal act that  involves unjustified threats to make a  money or property, or to cause loss to another.
It includes demanding money from someone and in return compromising information would not be revealed.

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.

Sector is best defined as (part).