Task: Question Answering
Input (English): Students want to compare the size of microorganism communities in 500-milliliter water samples from each of two ponds. Which factor most likely will affect the accuracy of their observations?  
 (A) the average temperature of the water samples (B) the brand of microscope slide used (C) the magnifying power of the microscope (D) the proper identification of each microorganism
Output (English): C