The four lines observed in the visible emission spectrum of hydrogen tell us that

The correct answer is violet, blue, green, and red emission lines.

Explanation:

When samples of pure elements are heated they emit a continuous spectrum of electromagnetic radiation. When elements are heated at very high temperatures, the electrons get excited and they jump to consequent orbits and this results in transmission of electromagnetic radiation. The four lines visible in the emission spectrum of hydrogen are violet, blue, green, and red, the most intense of which is at 656 nanometre.