Answer:
D. Matter as a wave
Step-by-step explanation:
electron is taken as particle because it is considered with small mass and charge. While electron in motion it also exhibit many properties similar to particles.
Like we can write the momentum associated with an electron given by

so in that all explanation if we have to find the interference due to electrons then we can say by De Broglie hypothesis that wavelength associated with moving electrons is given as

now as per this theory electron also shows the property of interference and diffraction.
so here we will have correct answer as
D. Matter as a wave