1) The Red Sox should stop penny-pinching and sign Jordan Montgomery
The other two options would make Boston marginally better, but if their plan is to seriously compete for a playoff spot in the hardest division in baseball, they need to go out and get a legitimate ace. Jordan Montgomery has proven in the last two seasons, and showed once again in the playoffs, that he is a legitimate ace. He's not Gerrit Cole or Corbin Burnes, but he can go out and win anytime he takes the ball.
It's time for the Red Sox to stop playing around. They have a glaring need for a frontline starter, and Montgomery happens to literally be in their backyard as we speak. His wife began a residency program in Beantown this winter, so Montgomery is with her. Assuming he likes the city, it's a slam dunk.
This past season, the southpaw posted a 3.20 ERA in 32 starts and 188.2 innings pitched. He got better and better as the season progressed, pitching extremely well for the Rangers to squeak into the playoffs, and then took his game up another notch in October helping them win the World Series. He's the kind of difference-maker competitive teams sign when they're trying to win.
If it means a guy like Kenley Jansen has to be traded to make room (it shouldn't), so be it. The Red Sox have enough bullpen pieces to survive without Kenley. Their rotation, however, will keep them out of games if they don't sign a guy like Montgomery to pitch deep and effectively into games every fifth day.
Is it realistic? At this point, probably not. However, the longer Montgomery stays unsigned, the more likely it is that his demands will drop. There has to be some price Boston will be willing to spend to get a pitcher of his caliber, right?