Coordinating Conjuctions

Just a quick exercise I thought up to justify the comma-conjunction rule when coordinating two complete sentences, even when they have the same subject.

A) "I was in deep trouble. I had forgotten Valentine's Day again. I went to the candy shop, and I bought a flower. My girlfriend had always wanted a chocolate rose. ..."

B) "I was in deep trouble. I had forgotten Valentine's Day again. I went to the candy shop and I bought a flower. My girlfriend had always wanted a chocolate rose. ..."

C) "I was in deep trouble. I had forgotten Valentine's Day again. I went to the candy shop and bought a flower. My girlfriend had always wanted a chocolate rose. ..."

D) "I was in deep trouble. I had forgotten Valentine's Day again. I went to the candy shop. I bought a flower. My girlfriend had always wanted a chocolate rose. ..."

E) "I was in deep trouble. I had forgotten Valentine's Day again. I went to the candy shop. And I bought a flower. My girlfriend had always wanted a chocolate rose. ..."

This story can have two endings. Had I managed to find a chocolate rose or not? Had I bought the flower  at the candy shop, or was it simply something I did afterward?

1) "She would have to wait another year."

2) "It would be my one ticket out of this mess."

Obviously I wrote these intentionally being unclear, but it is interesting to consider the different situations such  small changes might imply. To me, 1 most easily completes A, while 2 most easily completes B. B is technically not a grammatical sentence according to the style guides I learned, but I think it would be acceptable if you were finishing with 2, especially if you wanted to create a bit of dramatic tension in the reader.

C is the clearest. It could only with 2 unless you wanted to intentionally mislead the reader. D seems to be the most neutral between 1 and 2. It is also jarring enough that you would have to have a pretty good reason to use it. D and B are opposites most ways, but they are similar in that neither is a sentence you would write if you only wanted to convey simple meaning, which is why they are the most interesting.

E is grammatically correct, but stylistically bad according to many. I have no problems with starting sentences with conjunctions. But doing it too often generally leads to sloppy writing, so it something I tended to encourage my students to avoid if possible. 1 is the most natural ending to E, with the added implication that the speaker was especially worried about his girlfriend's wrath.

As a side note: fleshing this out has been a perfect example of how pointless questions like these are on standardized tests. It would be funny if the rise of emoticons came from people slowly becoming less proficient with style/grammar as a tool because it was made a painful end goal by the addition of the writing section to the SAT.