Some analysts point out that because people are becoming accustomed to

Must respect the sentence’s parallelism. Thus look at D,E
E is wordy and awkward
D is the answer

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My reasoning, between D and E,
in E, it feels like businesses are doing two actions:
Businesses are finding that they
1. can raise prices according to this amount
2. will not thereby provoke strong public reaction.
this is not the case, second event is providing more information about first action or is linked to first action.

D explains that relationship in a better way

­Some analysts point out that because people are becoming accustomed to a steady inflation rate of four to five percent, businesses found that they could raise prices according to this amount without thereby provoking strong public reaction.
 
 (A) found that they could raise prices according to this amount without thereby provoking (Incorrect: tenses and parallelism error)
Found is not parallel with are becoming. Because x therefore y. second if main clause is in present second should be in present hence it should be find instead of found
 (B) found that they were capable of raising prices by this amount and not provoke (incorrect: tenses and parallelism error)
 (C) find that they are capable of raising prices by this amount and not provoke (incorrect: parallelism error)
People are becoming, and Find are not parallel 
 (D) are finding that they can raise prices by this amount without provoking (the best option)
Maintaining parallelism and clear with meaning
 (E) are finding that they can raise prices according to this amount and will not thereby provoke (incorrect: incorrect meaning)
According to this amount means the amount is raising the price though the meaning should be till the amount.