premise - 1 : In the past six pro football drafts, 4 out of 6 players selected by team A are now starting on the squad.
Premise - 2 : On team B, only 2 out of the 6 players selected in the draft are starters.
Conclusion : So, a football player selected by team A from the draft pool has a higher probability of becoming a starter than if he is selected by team B.

assumption : The "methodology" for selecting players used by both the team that was prevelant in the past will be same for this year and all other factor prevalent in the past that have contributed to the higher probability of the players of team A in becoming a starter in the squad will remain the same. ( assumption in a defender role )

A - irrelevant
B - Though the new owner and the coaching staff may lead to a change in the so called "other factors" but still nothing is mentioned in this answer choice. How "the changes" will effect ?
C- Same like B .
Moreover the assumption that will work for B will also work for C ( the change in "other factors", which we have to assume, will contribute to the success of the players in team B ). We cannot choose both. So there must be some better answer that B and C.
D - Irrelavant
E - This is quite true about the "methodology" of the selection procedure. If team B had the first peak than it will choose the best player that team A had done in the past . Hence this is a weakening the argument.

E- Considering teams are biased

For this question, I think it is easier to eliminate the answer choices and zero in on the right one
The first four choices are all irrelevant as the conclusion drawn talks about a player being selected by Team A to have a higher probability than that by Team B of becoming a starter