In the following question, a sentence is divided into

Solution

The error is in part A of the sentence. The error in part A lies in the incorrect comparison structure. The comparative form "harder" should be used instead of "hard." When making a comparison between two things, the comparative form of the adjective is needed. The given sentence implies that quantum physics is more difficult to understand than classical mechanics, indicating a comparison. But, the phrase "hard to grasp" does not directly establish a comparison between the two subjects. Accordingly, the comparative form 'harder' should be used to convey the comparison appropriately. The correct sentence is: Quantum physics is harder to grasp than classical mechanics due to its abstract nature and complex mathematical formulations.