The following sentence has been split into four segments. Identify the segment that
contains a grammatical error and select the option which rectifies that error.
The space agency wanted / to test with a chimp / before orbiting a astronaut / in a
Mercury capsule.

Correct option is C

The error is in the phrase "before orbiting a astronaut." The article "a" should be "an" because the word "astronaut" starts with a vowel sound.
· Grammatical rule used: Use "an" before words that start with a vowel sound to ensure the sentence flows smoothly and is grammatically correct.
· Example: The program was successful because it was tested thoroughly before orbiting an astronaut.