Final answer:
Section 3 of the chart is where a bill is first debated in subcommittees, involving amending and working on the bill before it is sent back to the full legislative chamber.
Step-by-step explanation:
The section of the legislative process chart representing the point at which a bill is first debated in subcommittees corresponds to action number 3.
When a bill or resolution is considered, one of the actions taken by a committee or subcommittee is to perfect the measure by amending the bill. This involves working on the bill, debating, and amending it before it's sent back to the full Senate or House with a report describing its purpose.
Therefore, section 3 on your chart is where the bill is first debated in subcommittees.