In the question given below, four sentences have been given. Out of four sentences, one sentence is grammatically and contextually correct. Find out which of the following sentences is correct. If all the given sentences are correct, then choose option ‘All are correct’ as the answer choice.

Correct option is C

Analysis and Explanation for Each Sentence:
(a) The scientist conducted a experiment to test the new theory.
Error: "a experiment" → Incorrect article usage
Rule: The article "a" is used before words that begin with a consonant sound, while "an" is used before words that begin with a vowel sound. Since "experiment" starts with a vowel sound (/ɛkspərɪmənt/), it should be preceded by "an" instead of "a."
Corrected sentence: The scientist conducted an experiment to test the new theory.
(b) The train arrives on the station at exactly 10 AM.
Error: "on the station" → Incorrect preposition usage
Rule: The preposition "at" is used when referring to specific points or locations, whereas "on" is used when referring to surfaces. Since "station" is considered a point/location, the correct preposition is "at."
Corrected sentence: The train arrives at the station at exactly 10 AM.
(c) Farmers harvested their crops before the rainy season began.
This sentence is grammatically and contextually correct.
Rule:
1. "Harvested" (past tense) correctly agrees with "began" (past tense), maintaining tense consistency.
2. The conjunction "before" is correctly used to indicate the sequence of events.
(d) He practice yoga every morning to stay healthy.
Error: "He practice" → Incorrect subject-verb agreement
Rule: In the simple present tense, when the subject is singular (he/she/it), the verb must take the -s form. The verb "practice" should be in its third-person singular form, "practices."
Corrected sentence: He practices yoga every morning to stay healthy.
Correct Answer:
(c) Farmers harvested their crops before the rainy season began.