Identify the error in the sentence.
Mount Everest is the most highest mountain in the world.

Correct option is C

Option (c) contains an error.
Detailed explanation: The phrase “most highest” is a double superlative, which is grammatically incorrect. The adjective high forms its superlative as highest (not most high in standard usage). We should use only one superlative marker and include the article the before it.
Correct sentence: Mount Everest is the highest mountain in the world.
Grammatical rule used:
· Use -est for short adjectives (high → higher → highest).
· Do not combine most with an -est form (avoid double comparatives/superlatives like more better, most fastest).
· Example:
· Incorrect: She is the most oldest member of the team.
· Correct: She is the oldest member of the team.
· Information booster:
· Use more/most with long adjectives (e.g., more interesting, most beautiful).
· With short adjectives that take -er/-est, don’t add more/most (taller/highest, not more tall/most highest).