Question

Matter waves are:

• A. Electromagnetic waves
• B. Mechanical waves
• C. Either mechanical or electromagnetic waves
• D. Neither mechanical nor electromagnetic waves

Answer 1

The correct option is D Neither mechanical nor electromagnetic waves

it is a wave associated with particles revolving in an atom around nucleus. De broglie named these waves as matter waves or De Broglie's waves. its wavelength is calculated from wavelength $\lambda =h/mv$,
where, h is plank constant.
This theory mainly conveys the wave nature of light having energy given by plank $E=hv$. (v is frequency of radiation).
These waves do not require any material medium for it propagation. it is coming in mainly non relativistic theory.