Depending on how many marks in the exam, you can actually elaborate further, i.e. the impact of the MM experiment-remember the concept of aether at the time underlined many physics theory, and hence, the consistency of the null result obtained-despite different altitudes and geographic location-can arguably be
1) it compelled other independent groups to repeat the experiment, getting the same results-and hence confirm the reliability of the result
2)it may not have necessarily lead to Einstein formulating his theory of special relativity-I read it in a textbook somewhere that Einstein did not know about the experiment at the time, but rather, it unintentionally provided experimental proof for the first postulate of the special theory of relativity-which is the speed of light is constant c, so if both frames of reference are inertial, no mechanical experiment will be able to differentiate speed of light variations in the same medium-i.e. air/vacuum
3)It actually stimulated discussions, i.e. it compelled opponents of the experiment-i.e. supporters of the aether model to propose a variety of non-experimentally proven explanations as modifications of the aether model to explain the experimental results-but without experimental evidence, not very strong argument
4) it compelled sceptics of the aether model to support Einstein's theory of special relativity, and since Einstein now has experimental proof for a part of his theory, it means that more people within the scientific community was more readily willing to accept his theory-and therefore start to test for the preceding implications i.e. mass dilation etc-it is likely had it not been for MM experiment, no one could have paid much attention to Einstein's theory-because it was all theoretical and current technology at the time were inadequate to provide experimental proof
