Answer:
Metaphor is used in “My heart was a heavy rock in my chest”.
Explanation:
The metaphor is a figure of speech which compares one thing with another thing. The compared thing or word will not have the literal meaning of the given thing. This is based on the imagination of the writer. Metaphor gives life for the mere words and is used in poetry, literature and in our daily speech. There are numerous types of metaphor namely, implied metaphor, sustained metaphor, dead metaphor, mixed metaphor, and so on.
In the given sentence, the heart is compared to the heavy rock. From this sentence, we should not take the literal meaning and get that the heart is transformed into rock. This sentence conveys that the person is sad or in remorse. The meaning of the sentence is carrying a heavy rock is hard and tiresome, likewise when we are upset or sad, it is hard and tiresome for a person to think straight.