The answer is C) Orbits the Nucleus
This for health and hazard purposes. The conventional thermometers contain mercury which is very dangerous to health. It is toxic which could cause poisoning, respiratory damage and kidney problems. Because of this, it is already illegal to use them for safety purposes. Temperature probes are much safer because they only use thermocouples.
The pH unit has 10x as many hydrogens ions as the unit above.
Ex: A pH of 5 would have 10x more hydrogen ions than a pH of 6
and 100x more than if it had a pH of 7.
With a pH of 9 and 3, this is equivalent to 10⁶
So your answer should be:
1,000,000