What is the name of the branch with the greatest amount of memberships that were registered in the year 2016?
SELECT T2.name FROM membership_register_branch AS T1 JOIN branch AS T2 ON T1.branch_id   =   T2.branch_id WHERE T1.register_year   =   2016 GROUP BY T2.branch_id ORDER BY count ( * )  DESC LIMIT 1
greatest amount of memberships registered in year 2016 refers to MAX(COUNT(*)) WHERE register_year = 2016; branch with the greatest amount refers to selecting the branch name after joining with the branch table based on branch_id;