## Core Concept
The question tests the understanding of radioactive decay and the types of radiation emitted by different isotopes. Gamma radiation is a type of electromagnetic radiation, often emitted by radioactive isotopes during gamma decay.

## Why the Correct Answer is Right
The correct answer, , emits gamma radiations only because it is a metastable nuclear isomer that decays to its ground state by emitting gamma rays. This process does not involve the emission of alpha or beta particles, making it a pure gamma emitter.

## Why Each Wrong Option is Incorrect
* **Option A:** emits alpha particles. Alpha particles are high-energy helium nuclei that are emitted from the nucleus during certain types of radioactive decay.
* **Option B:** emits beta particles. Beta particles are electrons or positrons emitted from the nucleus during beta decay.
* **Option D:** emits alpha and gamma radiations. The emission of both alpha particles and gamma rays indicates a more complex decay process.

## Clinical Pearl / High-Yield Fact
A key point to remember is that (Technetium-99m) is commonly used in nuclear medicine for diagnostic imaging because it is a pure gamma emitter, making it ideal for imaging without causing damage to tissues through alpha or beta radiation.

## Correct Answer: C.