Choose the word or set of words that, when inserted in the sentence, best fits the meaning of the sentence as a whole.
The mountain road was distinct ----: it twisted back and forth along the contours of the hillside.
A. panoramic
B. precipitous
C. serpentine
D. circumscribed
E. retrograde

Hint: If we look at the sentence carefully, the blank space is followed by a colon, which means the phrase ‘it twisted back and forth along the contours of the hillside’, explains the meaning of the word to be filled in the blank. We are talking about a visual description of the mountain road here. So let us look for the word which best describes this the best.

Complete step by step answer:
Let us analyze each option individually in detail to know the correct answer.

Panoramic: By substituting this word, the complete sentence will be ‘The mountain road was distinctly panoramic: it twisted back and forth along the contours of the hillside’. The word panoramic means a wide and unobstructed view in all directions. Example: The sunrise at the beach was panoramic. This doesn’t justify the meaning given in the sentence, therefore this is an incorrect option.
Precipitous: By substituting this word, the complete sentence will be ‘The mountain road was distinctly precipitous: it twisted back and forth along the contours of the hillside’. The word precipitous means extremely steep. Example: A precipitous wall. This doesn’t justify the meaning given in the sentence, therefore this is an incorrect option.
Serpentine: By substituting this word, the complete sentence will be ‘The mountain road was distinctly serpentine: it twisted back and forth along the contours of the hillside’. The word serpentine means as a road, winding in nature, that is, with twists and bends. Example: The stream serpentines through the village. This justifies the meaning given in the sentence, therefore this is a correct option.
Circumscribed: By substituting this word, the complete sentence will be ‘The mountain road was distinctly circumscribed: it twisted back and forth along the contours of the hillside’. The word circumscribed means to bound with a boundary, encircle, enclose. Example: The village is circumscribed by a river. This doesn’t justify the meaning given in the sentence, therefore this is an incorrect option.
Retrograde: By substituting this word, the complete sentence will be ‘The mountain road was distinctly retrograde: it twisted back and forth along the contours of the hillside’. The word retrograde means moving in a backward motion, revert. Example: The troops retrograded by the overpowering enemies. This doesn’t justify the meaning given in the sentence, therefore this is an incorrect option.

So, the correct answer is “Option C”.

Note:
The correct answer serpentine correctly describes the phrase ‘it twisted back and forth’ given in the sentence which means bends and twists. Therefore, this is why we chose this option. Other synonyms of the word ‘serpentine’ are curved, circuitous. The roads curved along the river in parallel.