Reading Comprehension (RC) | Re: In most earthquakes the Earth’s crust cracks

For Q 6 the correct answer, option D, suggests that both stress and fracture must take place in order forANY earthquake to occur. But the following lines suggest that in case of the less common earthquakes fracture doesent occur. So If my understanding is correct, the answer should be A (only Stress).

"where high pressure makes rock so ductile that it flows instead of cracking" &
"how can such quakes occur, given that mantle rock at a depth of more than 50 kilometers is too
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