Directions: Each item consists of a sentence with underlined word/words followed by four words. Select the word that is nearest in meaning to the underlined word/words. These were based primarily in Himachal Pradesh, where the treks were as gruelling as the terrain.

Step-by-step solution

The word 'gruelling' means extremely tiring and demanding. 'Rigorous' means harsh, demanding, or strict, which is the closest in meaning to 'gruelling' in the context of a difficult trek. 'Egregious' means outstandingly bad or shocking. 'Unctuous' means excessively flattering or oily. 'Ominous' means giving the impression that something bad is going to happen. Therefore, 'rigorous' is the correct synonym. Answer: rigorous