Final answer:
Without specific context, Class 4 Instructors would generally be supervised by only senior instructors or any certified instructor, depending on the specifics of the supervisory qualifications required.
Step-by-step explanation:
The question regarding who can supervise Class 4 Instructors is not specific to a widely recognized standard or system. Typically, the supervision of instructors would depend on the regulations of the educational system or institution in question. However, in general, supervision would ordinarily be conducted by individuals who have a higher level of experience or certification than those they are supervising. Therefore, without specific context, the most likely correct answer would be only senior instructors or any certified instructor if the certification process includes the ability to supervise others.