The equation
`4H^(+) rarr _(2)^(4) He^(2+) + 2e bar + 26 MeV represents`

Options

A. `beta`-decay
B. `gamma`-decay
C. fusion
D. fission

Explanation

To solve the question regarding the equation \( 4H^{+} \rightarrow _{2}^{4}He^{2+} + 2\bar{e} + 26 \text{ MeV} \), we will analyze the components of the reaction step by step.

### Step 1: Identify the reactants and products
The equation shows that 4 protons (hydrogen nuclei, \( H^{+} \)) are combining to form a helium nucleus (\( _{2}^{4}He^{2+} \)), along with the emission of two positrons (\( 2\bar{e} \)) and the release of energy (26 MeV).

**Hint:** Look for the particles involved in the reaction and their transformations.

### Step 2: Understand the process taking place
The process described involves the combination of smaller nuclei (hydrogen) to form a larger nucleus (helium). This is indicative of nuclear fusion, where light nuclei fuse to create a heavier nucleus.

**Hint:** Recall the definition of nuclear fusion and how it differs from fission.

### Step 3: Analyze the energy release
The reaction releases 26 MeV of energy, which is typical in fusion reactions. This energy release occurs because the binding energy per nucleon increases when lighter nuclei fuse to form a heavier nucleus, resulting in a more stable configuration.

**Hint:** Consider the concept of binding energy and how it relates to the stability of nuclei.

### Step 4: Determine the type of decay or reaction
Since the reaction involves the combination of nuclei and the emission of positrons, it is not a decay process like beta decay or gamma decay. Instead, it is a fusion reaction where smaller nuclei combine to form a larger nucleus.

**Hint:** Differentiate between fusion, fission, and decay processes based on the changes in nuclear structure.

### Conclusion
Based on the analysis, the equation represents a nuclear fusion process where four hydrogen nuclei combine to form one helium nucleus, releasing energy and emitting positrons. Therefore, the correct answer is that this process is nuclear fusion.

**Final Answer:** The equation represents nuclear fusion.