The large onion-shaped receptors that are found deep in the dermis and in subcutaneous tissue and that respond to deep pressure are
a. Epithelial tactile complexes
b. Lamellar corpuscles
c. Free nerve endings
d. Muscle spindles

Lamellar corpuscles, also known as Pacinian corpuscles, are large, onion-shaped sensory receptors located deep in the dermis and subcutaneous tissue. They are specialized to detect deep pressure and vibration stimuli, making them essential for sensing mechanical changes beneath the skin surface.

Epithelial tactile complexes, or Merkel cells, are sensory receptors found in the basal layer of the epidermis. They respond primarily to light touch and texture, providing detailed information about objects in contact with the skin, but are not involved in sensing deep pressure.

Free nerve endings are unspecialized nerve fibers that detect pain, temperature, and crude touch, while muscle spindles are sensory receptors within muscles that monitor stretch and muscle length. Neither is responsible for detecting deep pressure in the skin.