Technician a says that tie rod ends are used to connect the steering linkage to the steering knuckles. technician b says that some ball and socket joints are sealed and do not require lubrication. which technician is correct

Both technicians A and B are correct.                

Explanation:

The tie rod is present as a part  of a steering system. It consists of inner end as well as  outer end. It helps in transferring force from the steering link to the steering knuckle. And this causes to turn the wheel of the vehicle.

Usually a ball joint comes with pre-greased. The sealed ball and socket joint are lubed for their life, so they does not require lubrication.

Thus both the technicians are correct.

the independent variable, or the one that is intentionally manipulated is the speed.