In each of the questions given below, four sentences have been given. One out of four sentences may or may not contain an error. Find out which of the following sentence has an error. If all the sentences are error-free then choose ‘ All are correct’ as your answer choice.

The correct option containing an error is: "Nothing is ever constants and change will always be the order of the day."

Step-by-Step Explanation:
1. Analyze the Grammar & Syntax:
In the sentence "Nothing is ever constants and change will always be the order of the day," the word "is" is a singular verb modified by the adverb "ever". It links the subject pronoun "Nothing" (which is singular) to its complement predicate adjective/noun.
2. Identify the Grammatical Error:
The word "constants" is a plural noun. However, in this context, the modifier/complement should be the singular adjective "constant" (meaning unchanging or continuous). Therefore, using the plural form "constants" is grammatically incorrect.
3. Corrected Sentence:
"Nothing is ever constant and change will always be the order of the day."

Review of Other Options:
• "The students who went back home did not return." - Grammatically correct.
• "The major reason behind pollution is stubble burning across the country." - Grammatically correct.
• "India’s population is among the youngest in the world." - Grammatically correct.