I think E is better unsupported by the fact that it is never stipulated that any antibiotics have been used on bacteria X at all.

How is this logic wrong?

SAS -> /V

/SAS -> AA (if she does not deliver her speech then the assassination attempt did not fail (it succeeded). Which we get from group 3 negate sufficient. Contrapositive follows that:

/AA -> SAS

And thus: /AA -> /V

If the assassination attempt failed, then the vote did not pass.