[单选题]
The energy an electromfnvi0ha1 s47bk fk 2hw swj.*:agnety7+e ebonb 644420qhvw;;h s* sfzcrvpmc x0tic wave transports per unit time per unit area is thesec+27* 0;yne4svb; oq4ch t4 m0vw br6hxpfz
A. energy density.
B. power.
C. intensity.
D. radiation pressure.
