In a lab class, different groups of students are using ohmmeters to test the strengths of different batteries. when a group has a question about their ohmmeter, who is the best person to ask for ? the student with the highest grades a student whose lab group is finished the instructor who is leading the lab a student whose mom is an electrician

The best answer would be the instructor who is leading the lab. 

The student with the highest grades is not a reliable source because there is no assurance that they would know how to use the ohmmeter. A student whose mom is an electrician would not be a good choice because just because the mom is an electrician, it does not automatically mean that the student himself would know how to use an ohmmeter. 

The best source of information would then be the instructor leading the lab because they are there to guide you through the lab class.