129) Work study comprises following main techniques

Answer is:

method study and work measurement

Explanation:

Work study consists of two techniques namely method study and work measurement.
The method study is a technique to simplify the job and develop more economical methods of doing it.
The Work measurement is concerned with the elimination of ineffective time and establishment of time standards for a job.
Work study is mainly aimed at determining the most efficient method of performing a job. Basic tool in work study is stop watch.