Which term from the past describes the sharing of mainframe computing resources?

Which term from the past describes the sharing of mainframe computing resources?

• XaaS
• Time-sharing
• Time division multiplexing
• Mainframe sharing 

 

EXPLANATION

Time-sharing allowed groups of people to use expensive mainframe computing resources concurrently by working in isolated computing sessions.
Time division multiplexing is a signal transmission protocol.
Mainframe sharing is not an industry-accepted term.
XaaS refers to any web service delivered over the Internet (Anything as a Service) and thus is incorrect