writing question

the harsh conditions in which bristlecone pine trees live may help to explain their exeptional longevity, (because those same conditions are also inhospitable to) the pests that can attack the trees.

i didn’t understand why its correct. if i start a new clause with a comma i should start with “for” and not “because”. i disqualified the answers with “because” immediately

Both because and for work well. They are both conjunctions linking two parts of the sentence.

Is that a real College Board sentence? CB’s usual rule is DC-comma-IC not IC-comma-DC…

yes it’s from a former test

Wow, what year?