To prepare for a group discussion on his own, it would be best for Tomas to begin by working with the group to establish roles.
establishing the discussion’s goals.
setting the rules for the discussion.
researching the topic.

D.   researching the topic.

Explanation:

The question says what would be best for Tomas to do on his own and the answer to that is to research the topic.

on april 6, 1917, the u.s. joined its allies--britain, france, and russia--to fight in world war i. under the command of major general john j. pershing, more than 2 million u.s. soldiers fought on battlefields in france.

they usually pass federal laws

and sometimes in the elections of the president