Final answer:
The new subset of a data warehouse created for a new department in a company is called a data mart, specifically designed to meet the department's data requirements.
Step-by-step explanation:
When a company starts a new department and creates a new subset of a data warehouse to hold data specific to that department, this new subset is commonly referred to as a data mart. A data mart is a smaller, more focused portion of a data warehouse and is designed to cater to the specific needs of an individual department within an organization.
By tailoring the structure and content to the department's requirements, a data mart provides relevant data in a more accessible and efficient manner for business analyses and departmental functions.