Complete the passage by filling in the blanks with the most appropriate words.
The ancient civilizations of Mesopotamia, Egypt, and the Indus Valley were among the first to develop complex societies, relying on agriculture as the cornerstone of their economies. In Mesopotamia, the Sumerians created the first known form of writing, ____A____cuneiform, which was inscribed on clay tablets. This form of communication enabled the recording of important events, laws, and even trade transactions, ____B____ the foundation for future generations to understand their past.
In Ancient Egypt, the great pyramids stand as a testament to the engineering prowess of the civilization. The construction of these monumental structures required careful planning and ____C____ skilled workforce. However, much of the wealth generated through agriculture and conquest was concentrated in the hands of the elite, which led to the emergence of ____D____ between the ruling class and the common people.
Similarly, the Indus Valley Civilization, known for its advanced urban planning, fell into decline for reasons that remain ____E____. Some scholars argue that environmental factors, such as shifts in river patterns, may have played a significant role in the civilization's collapse. Nevertheless, the achievements of these early societies paved the way for future innovations in science, technology, and governance.
Choose the correct word to fill in blank (E) and complete the sentence.
Show answer & explanation
Correct answer: C
Explanation
Correct Answer
(c) unclear
Explanation
The sentence states that scholars are still arguing over what exactly caused the collapse of the Indus Valley Civilization (such as shifts in river patterns). Because experts are presenting different theories and do not have a single definitive answer, the reasons for its decline remain 'unclear' (not certain or unknown).
The other options are incorrect because they contradict the context or make no grammatical sense. Option (a) 'clear' is the opposite of what the passage implies. Options (b) 'cleared' and (d) 'uncleared' are past participle verb forms related to cleaning or removing obstacles, which do not fit contextually.
Key Points
When a passage presents active debates or multiple competing theories among researchers ('Some scholars argue...'), it indicates that the core topic is not yet fully understood. This context automatically points you toward answers that mean unknown or uncertain.