A jet engine undergoing ground testing vents its exhaust through a smokestack. Investigators set up two probes to measure the dispersion of the exhaust into the atmosphere. Probe A is set up at a fixed location near the exit of the smokestack. Probe B is attached to a balloon that is carried along by the local air current which, for the purposes of this analysis, will assumed to be steady. Define what type of derivatives these probes represent and identify which probe corresponds to which type of