Radioactively Labeled Probe Detection:

Autoradiography:
Autoradiography is a technique used to visualize the location of radioactively labeled molecules in a sample. In the context of a radioactively labeled probe, autoradiography can be used to detect the presence of the probe in a biological sample.

- Autoradiography involves exposing the sample to a photographic film or an imaging plate.
- The radioactively labeled probe emits radiation in the form of radioactive decay.
- This radiation exposes the photographic film or imaging plate, resulting in dark spots or bands.
- The dark spots or bands correspond to the location of the radioactively labeled probe in the sample.
- By analyzing the autoradiograph, researchers can determine the presence and location of the radioactively labeled probe.

UV Rays:
UV rays, or ultraviolet rays, are not typically used for the detection of radioactively labeled probes. UV rays are a form of electromagnetic radiation with a shorter wavelength than visible light.

- UV rays are commonly used for various applications such as DNA visualization in gel electrophoresis.
- However, UV rays do not have the ability to detect radioactively labeled probes directly.
- Radioactive labeling involves the incorporation of a radioactive isotope, which emits radiation that can be detected by other methods such as autoradiography.

ELISA:
ELISA, or enzyme-linked immunosorbent assay, is a technique used to detect and quantify the presence of specific molecules in a sample. However, ELISA is not specifically designed for the detection of radioactively labeled probes.

- ELISA typically relies on the use of enzymes and antibodies to detect specific molecules.
- It can be used to detect proteins, antibodies, and other molecules of interest.
- Radioactively labeled probes do not involve the use of enzymes or antibodies, making ELISA less suitable for their detection.

PCR:
PCR, or polymerase chain reaction, is a technique used to amplify specific DNA sequences. It is not directly used for the detection of radioactively labeled probes.

- PCR involves multiple cycles of DNA denaturation, primer annealing, and DNA synthesis.
- It is commonly used to amplify and detect specific DNA sequences.
- However, PCR does not directly detect radioactively labeled probes.
- After PCR amplification, the presence of radioactively labeled probes can be detected using autoradiography or other appropriate methods.

Conclusion:
The correct answer is option 'A' - Autoradiography. Autoradiography is specifically designed for the detection of radioactively labeled probes by visualizing the location of the probe in a sample through exposure to a photographic film or imaging plate. UV rays, ELISA, and PCR are not directly used for the detection of radioactively labeled probes.