Updated: Dec 9, 2025 | Source: 2024-2028 Question Pool | Topic: E3C
E3C07E3C

Which of the following indicates the greatest solar flare intensity?

Deep Dive: E3C07

The correct answer is D: Class X. Which of the following indicates the greatest solar flare intensity is Class X. Solar flares are classified A, B, C, M, X (increasing intensity), with X being the strongest. For amateur radio operators, this is important for understanding space weather. Understanding this helps when evaluating solar activity.

Why Other Answers Are Wrong

Option A (Class A): Incorrect. Class A is the weakest, not greatest - Class X is the strongest. Class A is weakest. Option B (Class Z): Incorrect. Class Z doesn't exist - solar flares go A, B, C, M, X. Class Z doesn't exist. Option C (Class M): Incorrect. Class M is strong but not the greatest - Class X is the strongest. Class M isn't the greatest.

Exam Tip

Greatest solar flare intensity = Class X. Think 'S'olar 'F'lare = 'X'treme (strongest). Solar flares are classified A, B, C, M, X (increasing intensity), with X being the strongest. Not Class A, not Class Z, not Class M - just Class X.

Memory Aid

Greatest solar flare intensity = Class X. Think 'S'olar 'F'lare = 'X'treme. Solar flares are classified A, B, C, M, X (increasing intensity), with X being the strongest. Important for understanding space weather.

Real-World Example

Solar flare intensity classification: Flares are classified A, B, C, M, X in increasing order of intensity. Class X is the greatest intensity - these are the most powerful flares that can cause severe radio blackouts. This is the class - Class X indicates the greatest solar flare intensity.

Source & Coverage

Question Pool: 2024-2028 Question Pool

Subelement: E3C

Reference: 2024-2028 Question Pool · E3 - Radio Wave Propagation

Key Concepts

Solar flare intensity Class X Greatest intensity Solar flare classification

Verified Content

Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E3C topic.