Electromagnetic spectrum ordered by increasing wavelength

Steps:

• Recall EM spectrum order: gamma rays (shortest wavelength), X-rays, ultraviolet, visible light, infrared, microwaves, radio waves (longest).
• Compare wavelengths: gamma < ultraviolet < infrared.
• Verify option A: gamma to ultraviolet to infrared shows steady increase.
• Eliminate options where sequence decreases or mixes orders.

Why A is correct:

• Gamma rays (~10^{-12} m), ultraviolet (~10^{-8} m), infrared (~10^{-6} m) follow the spectrum's wavelength progression per Planck's relation (λ ∝ 1/f).

Why the others are wrong:

• B: Infrared (long) to X-ray (short) decreases wavelength.
• C: Microwave (long) to X-ray (short) decreases wavelength.
• D: Ultraviolet to gamma ray reverses to shorter wavelength.

Final answer: A