Receptors which are sensitive to pain are
A. Tangoreceptors
B. Frigidoreceptors
C. Rheoreceptors
D. Algesireceptors

Hint: This receptor is also known as nociceptor that responds to damaging stimuli by sending possible threat signals to the brain and the spinal cord.

Complete Answer:
- Receptors are proteins, typically cell surface receptors that bind to ligands and trigger immune response, including cytokine receptors, FC receptors. In different immune cells such as B-cells, T-cells, NK cells, monocytes and stem cells, receptors are identified.
- Another small molecule such as a neurotransmitter, hormone, prescription drugs, poison or sections external to a virus or microbe is called a ligand that binds to a receptor, which may be a Peptide (Short Protein) or a small molecule.
- If a ligand binds to the receptor, it activates the corresponding biochemical pathway of the receptor, or inhibits it. Cell development, division and death may be caused by receptors; cell binding may be mediated by membrane channel or mediated. In signal transduction, immunology and immune responses, receptors play a significant role.
- Tangoreceptors are the receptors which respond to touch and pressure. These are the skin's dermal receptors. The skin receptors near the afferent neurons receive the neurotransmitters. The nerve impulse is produced by the neurotransmitters to the brain to be processed. The parietal lobe has a sensory contact field for touch.
- Frigidoreceptor is a cold-stimulated receptor.
- Thermoreceptors are a type of mechanoreceptors in aquatic animals that detect and respond accordingly to signal strengths of the water current.
- Analgesic Receptor is a receptor of the pain which is a naked nerve ending without any organized end organ, also termed as nociceptor.

Thus, the correct answer is option D. i.e., Analgesic Receptor.

Note: Receptors are composed of protein chemical structures that receive signals and transduce them that are integrated with biological systems. Usually, these signals are chemical messengers that bind to a receptor and induce certain types of response from cell or tissue.