Select the most appropriate meaning of the given idiom.

Get down to brass tacks.

To become serious about something

The most appropriate meaning of the idiom "get down to brass tacks" is to become serious about something.

The other options are incorrect.

• "Get fired from the job" does not mean to become serious about something. Getting fired from a job is a negative event, while becoming serious about something is a positive event.
• "Compromise, cooperation between people" does not mean to become serious about something. Compromise and cooperation are ways to resolve disagreements, while becoming serious about something is a way to focus on the task at hand.
• "To be ready" does not mean to become serious about something. Being ready means to be prepared, while becoming serious about something is a way to focus on the task at hand.

The idiom "get down to brass tacks" comes from the idea of brass tacks being the small nails that hold something together. In the same way, to get down to brass tacks means to focus on the essential details of something. For example, you might say that a business meeting is getting down to brass tacks when the participants start discussing the financial details of a deal.