There are two errors in the original sentence. First, the expression “causing the result of” is nonsensical; it is impossible for something “to cause the result of” something else. Either “an event causes an effect,” “an event results in an effect,” or “an effect is the result of an event.” Second, the expression “as many as” refers to a portion of the “population,” which is an uncountable noun (i.e., one cannot say “one population, two population”); hence, the correct expression here is “as much as” rather than “as many as.”

(A) This choice is incorrect as it repeats the original sentence.

(B) The expression “causing the result of” is nonsensical; it is impossible for something “to cause the result of” something else. This choice does correctly use "as much as" rather than “as many as” to refer to the unquantifiable noun "population."

(C) CORRECT. This choice correctly uses the expression “as much as” rather than “as many as” to refer to the uncountable noun “population.” In addition, this choice uses the grammatical form “Poor weather … created meager harvests resulting in X and Y” where the entire phrase beginning with “resulting” directly modifies “harvests,” and where X, “mass starvation … ,” and Y, “the elimination of … ” are parallel to each
other in structure.

(D) The expression “as many as” refers to a portion of the “population,” which is an uncountable noun; hence, the correct expression here is “as much as” rather than “as many as.” In addition, the construction “Poor weather…created meager harvests… and resulted in mass starvation …” changes the meaning of the sentence slightly by asserting that the poor weather, rather than the meager harvests, was the direct cause of the starvation and the elimination of some of the population.

(E) The expression “as many as” refers to a portion of the “population,” which is an uncountable noun; hence, the correct expression here is “as much as” rather than “as many as.”