Answer:
"In session": the time when Congress is active and members are present, fulfilling their respective duties.
Conference: a meeting for discussion.
Roll call vote: a voting process by the members who are present; no absentee voting allowed.
Sit: a bill that will not be in progress or in any action but will be inactive for a particular time period.
Floor action: activity concerning a bill which may include debates and compromises.
Version: a form or variation of the original.
Step-by-step explanation:
It´s said Congress is "in session" when it assembles and performs its regular business.
We talk about "version", for example, if the House and the Senate present different versions of a bill. And Conference Committees are needed if the House and the Senate present different versions of a bill, so they can discuss a compromise acceptable for both.
In a roll call vote, there´s a public record of the way each member voted, so there´s no absentee voting allowed.
There´s floor action when there´s action, discussions, and compromises regarding a bill. On the other hand, we talk about "sit" when a bill has no action and becomes inactive for a special period of time.