The common element in the three given terms is "People".
Step-by-step explanation:
The meaning of the given terms are as follows,
Emigrated: This means to leave own country or residence to settle in another country (or) Group who shares a common language, ancestry, religion, combination or customs of similar characteristics.
Steerage: The lower deck of the ship that gives room for the people with cheapest tickets (or) it refers to the cramped quarters in which the passengers who paid lower fares for tickets gets accommodated
Recruit: To make a person to join a job or quilt (or) hiring people for jobs
Common element: As all the three terms associated with passengers, group members, common people we can conclude that all are related to people.