Final answer:
The simple subject of the sentence is 'Puppy'. 'Playful Puppy' is the complete subject and 'Puppy' is the core element being discussed.
Step-by-step explanation:
The simple subject in the sentence "The Playful Puppy Jumped In The Mud Puddle" refers to the main noun that the sentence is about, without any of the additional describing words (adjectives) or phrases. In this case, the simple subject is "Puppy". While "Playful Puppy" serves as the complete subject, including the adjective describing the puppy, "Puppy" alone is the fundamental element that we're discussing when identifying the simple subject. The other options provided, such as "Mud Puddle" and "Jumped", are incorrect because "Mud Puddle" is the object the puppy interacts with, and "Jumped" is the verb describing the puppy's action.