Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: Electromagnetic waves transfer energy across space as well as through matter. They vary in their wavelengths and frequencies, and higher-frequency waves have more energy. The full range of wavelengths of electromagnetic waves, shown in the Figure below , is called the electromagnetic spectrum. Answer: matter
Output:
Electromagnetic waves transfer energy across space as well as through what?