Answer: c) can be easily employed with large groups of trainees
Explanation: Lecture is the form of presentation that is given on certain subject or topic to share, teach and present the information to audience. The motive of the lecture is imparting the knowledge by representing the data through presentation slides, orally etc.
Lectures can be used for teaching trainees group because they can be taught about the subject easily through oral and presentation method.
Other options are incorrect because feedback and involvement is dependent upon trainees activeness while lecture. It does not take huge amount of time and is cost-efficient method. The work place and training is based on performance of trainees , lecture can only make them learn about the field.
Thus, the correct option is option(c).