Answer:
D. Y and Z
Explanation:
From the data given, one can easily see that the maximum elevation achieved by river is 5.2 meters. Now the house Y has the elevation of 3.5 meter and house Z has elevation of 4 meters. Around 1:00 PM, when the flood level reaches at 4.0 meters, both Y and Z houses will be flooded badly. Since, House X has an elevation of 8 meters so it is completely safe. So option b and c are excluded.
Since, elevation of river would be higher than both Y and Z, so option a is also excluded and option d is the right answer.
