On the modified mercalli scale, what is the greatest intensity where people indoors can feel the motion, but people outdoors cannot?
a) i
b) xi
c) vii
d) iii

Option (D)

Explanation:

The modified Mercalli scale is commonly used by the geologists to determine the intensity of an earthquake. It also determines the amount of destruction it causes to an area. It has some standard values ranging in number from I to XII, where the value I is the least effective (almost unnoticeable) and XII is the most destruction. This scale was constructed based on the effect that an earthquake causes.

Thus, from the given condition, it can be concluded that the highest intensity felt by the people indoor and not by the outdoor people is III.

Hence, the correct answer is option (D).