I see a few questions about this one, and it is tricky. At the heart of the confusion lies an idiom, but we will address that in a moment. First, the unadulterated sentence:
DarkHorse2019
Because of the fear that the company's latest efforts to contain the spill, which had started three months ago when a leased rig sank, might falter, BP shares fell in London and New York.
Did you catch any mistakes?
DarkHorse2019
(A) had started three months ago when a leased rig sank, might falter, BP shares fell
The past perfect is incorrect here. The
which clause marker could be replaced by its referent,
the spill, and we should get a clear timeline of events. But
the spill had started... when a rig sank skews the order of events, making it sound as if the sinking came after the spill had already begun. I will save
when for my analysis of (C) below. For now, keep moving.
DarkHorse2019
(B) had started three months ago when a leased rig sank, might falter, BP shares had fallen
The same two errors persist, but now we have a third: the past perfect
had fallen does not agree with the potential outcome suggested by the earlier
might falter. One, two, three strikes you're out.
DarkHorse2019
(C) started three months ago when a leased rig sank, might falter, BP shares fell
It might sound okay, but
started... when is the wrong construct. The idiom should be
started... with instead. That is, the spill started
with some event, rather than saying that the spill started
when some event
verb-ed.
DarkHorse2019
(D) started three months ago with the sinking of a leased rig, might falter, BP shares fell
This choice opts for the correct idiom in
started... with, and the verb tense at the tail-end of the underlined portion agrees with the anticipated outcome: people were fearing that BP's efforts to contain an oil spill (presumably)
might falter, so the company's stock prices
fell in response.
DarkHorse2019
(E) started three months ago with the sinking of a leased rig, might falter, BP shares had fallen
Almost, but this is clearly a worse version of (D), provided you had caught the idiom
started... with in the first place. Stock shares
fell in response to a certain fear, rather than having fallen prior to that fear. The cause-and-effect arrow needs to be clear.
I hope that helps clear any doubts about (D). It is not that
start... when is incorrect 100 percent of the time--e.g,
His political career started when Nixon took office.--it is just that, as explained above, in the context of
this sentence, we are trying to say that an event started
with a catastrophe, rather than
when a catastrophe occurred.
Good luck with your studies.
- Andrew