To answer this question, the user needs to know the characteristics of a data warehouse.

A data warehouse is a large, centralized repository of data that is used for analysis and decision-making. It is designed to support business intelligence (BI) activities, such as reporting, data mining, and online analytical processing (OLAP).

Now, let's go through each option and explain why it is right or wrong:

A. Sub-second response time: This option is not a characteristic of a data warehouse. In fact, data warehouses are typically optimized for complex queries that involve large volumes of data, which can take some time to execute. They are not designed to provide sub-second response times.

B. Heterogeneous data sources: This is a characteristic of a data warehouse. Data warehouses are designed to integrate data from a wide variety of sources, such as databases, flat files, and external systems. This allows organizations to consolidate their data into a single repository for analysis.

C. Voluminous historical data: This is a characteristic of a data warehouse. Data warehouses are designed to store large volumes of historical data, which can be used for analysis and decision-making. This historical data is typically used to identify trends, patterns, and insights that can inform business strategies.

Therefore, the answer is: A. Sub-second response time.