Answer:
The correct answer is: a) it relies on testimony from people.
Explanation:
The Mercalli intensity scale, unlike the Richter scale, does not directly measure the energy of an earthquake. Rather, it takes into account the damage and effects that the earthquake caused. When there is little damage, it relies on the testimony of people who felt the earthquake, which may vary and is ultimately subjective to people's perception.
The Mercalli Intensity Scale ranges from "Not felt" to "Catastrophic" going through 12 scale intensities.