Parts of the following sentences have been given as options. Select the option that contains a grammatical error.
Ms. Malathi is living lonely in an apartment.

The correct option that contains a grammatical error is lonely in.

Detailed Explanation:
In the sentence "Ms. Malathi is living lonely in an apartment," the word "lonely" is used incorrectly.
"Lonely" is an adjective that describes a subjective emotional state of sadness caused by being alone (for example, "She felt lonely in the new city"). It cannot be used as an adverb to describe the physical state or manner of living.
To express that she is living by herself without other people, the adverb alone should be used instead of the adjective "lonely".

Corrected Sentence:
"Ms. Malathi is living alone in an apartment."