The correct answer is: A. different wages for different level of performance.
Differential piece wages is a wage system in which workers are paid a piece rate for each unit of output they produce. The piece rate is typically set so that workers who produce more units of output earn more money. This system is designed to motivate workers to produce more and to reward them for their productivity.
Option B is incorrect because it describes a time-based wage system, in which workers are paid a fixed amount for each hour they work. Option C is incorrect because it describes a piece-rate wage system, in which workers are paid a fixed amount for each unit of output they produce. Option D is incorrect because it describes a system in which workers are paid different wages based on the type of industry they work in.