Answer:
The author's use of foreign words makes this piece challenging.
Explanation:
This is the best way to explain the challenges that are present in a particular piece. The original sentence stated that "many things" were complicated. This is too vague and unlikely to help the reader understand what the difficulties consist of. Similarly, the other options use phrases such as "many confusing pieces," "full," "many challenges and pitfalls" and "many things." These are very vague and informal. The first option, however, states that the difficulty lies in the author's use of foreign words, which helps us understand the difficulties better.
