Official explanation:The original sentence suffers from three redundancies. First, the verb “to find” is redundant of “seeking.” Second, the phrase “once in every 4 weeks” is wordy and can be replaced with the more concise form “every 4 weeks” without any loss of content. Finally, the construction “exactly the same” is repetitive, since the word “the same” already implies exact equivalence.
(A) This answer choice is incorrect as it repeats the original sentence
(B) In this answer choice, the phrase “once in every 4 weeks” is wordy and can be replaced with the more concise form “every 4 weeks” without any loss of content. Moreover, the construction “exactly the same” is repetitive, since the word “the same” already implies exact equivalence. "In a row 3 times" is awkward.
(C) CORRECT. This answer choice corrects all of the original redundancies, thus creating a concise and idiomatic sentence. Specifically, the repetitive construction “seeking to find alternative explanations” is reduced to the simpler form “seeking alternative explanations.” Further, the redundant phrase “once in every 4 weeks” is replaced with the more concise construction “every 4 weeks.” Finally, the wordy phrase “exactly the same” is replaced with the more concise construction “the same.”
(D) In this answer choice, the construction “exactly the same” is repetitive, since the word “the same” already implies exact equivalence.
(E) This answer choice corrects the original problems but introduces the redundant pronoun “he” in the second part of the sentence, thus unnecessarily repeating the original subject “Jean-Baptiste Lamarck.” Furthermore, the construction “the same identical results” is redundant; the adjective “identical” can be omitted without any loss of content.