HOTSPOT
You have an OLAP cube named Cube1. Cube1 has two partitions named partition1 and
partition2.
You need to configure the storage mode for each cube partition.
The solution must meet the following requirements:
Users must be able to retrieve aggregate data from partition1 as quickly as possible.
The processing time for partition1 and partition2 must be minimized.
The least possible amount of storage must be used for partition2.
What should you do? To answer, select the appropriate storage mode for each partition in
the answer area.
Answer: 
Holap
Rolap
+1 because of “retrieve ->aggregate<- data from partition1"
Agree
agree.
ROLAP in partition 2 because of least possible amount of storage.
https://msdn.microsoft.com/en-us/library/ms174915.aspx
according your article. original answer is correct.
I agree with Chris, even though I thought initially Holpa – Rolap too