Pick the best option. The most common reason why data warehouses are not as normalized as OLTP databases $($in general$)$ is:

To improve query performance $($i$.$e$.$ make them faster$)$

To improve data storage requirements $($i$.$e$.$ save hard drive space$)$

To speed up the design of the system $($i$.$e$.$ concept to installation faster$)$

To allow the accessing applications to be less complex $($i$.$e$.$ less code$)$