*Question E3C07:
Which of the following indicates the greatest solar flare intensity?*  

*Correct Answer is  D: Class X*  

### AI Response: (may contain errors)  

Solar flares are classified based on their intensity, which is measured in terms of X-ray emissions. The classification system uses letters to denote different levels of intensity, with each class being ten times more powerful than the previous one.

1. **Correct Answer: Class X**
   - Class X flares are the most intense type of solar flares. They can cause significant disruptions to radio communications and power grids on Earth. The intensity of these flares is such that they can lead to widespread radio blackouts and even damage satellites.

2. **Why the other choices are incorrect:**
   - **Class A:** These are the weakest solar flares. They have minimal impact on Earth and are often not even noticeable in terms of radio communication.
   - **Class Z:** This is not a recognized classification for solar flares. The standard classes are A, B, C, M, and X.
   - **Class M:** These are medium-intensity flares. They can cause brief radio blackouts in the polar regions and minor radiation storms that might affect satellites.

3. **Useful Rule of Thumb:**
   - The classification system is logarithmic, meaning each class is ten times more powerful than the one before it. For example, a Class M flare is ten times more intense than a Class C flare, and a Class X flare is ten times more intense than a Class M flare.

Understanding the classification of solar flares is important for predicting their potential impact on radio communications and other technologies.