A metaphor is a piece of figurative language that compares two unlike things without using the terms "like" or "as". Off the bat, you can eliminate B and C, because they include these words. Option A is a piece of prose, it makes no comparisons.
The answer is D, because it compares the subject, "I" (most likely a person), to a rock (which is not a person).
Answer:— One of these therapies is equine therapy, which is therapy involving a horse. Autistic children have difficulty interacting and bonding emotionally with others. ... The child feels positively rewarded for speaking when the horse does what the child tells it to do.
Explanation: