Final answer:
If logrolling is allowed, Megan voting for the Soccer Field if Lindsay votes for the Theater can lead to only the 'right' projects being completed.
Step-by-step explanation:
In the given scenario, the logrolling scenario that can lead to only the 'right' projects being completed and the 'wrong' projects not being completed is when Megan will vote for the Soccer Field if Lindsay votes for the Theater. This is because Megan has a positive net benefit for the Soccer Field while Lindsay has a negative net benefit, and their votes will cancel each other out for the Theater project. Therefore, if this logrolling scenario occurs, only the Soccer Field project will be completed.