Which explanation could a student use to explain how electromagnetic and mechanical waves travel? O A Neither electromagnetic nor mechanical waves travel in a vacuum and neither transfers energy.
O B. Both electromagnetic and mechanical waves travel in a vacuum and they both transfer energy.
O C. Mechanical waves can travel through a vacuum and a medium and they transfer energy.
OD. Electromagnetic waves can travel through a vacuum and a medium and they transfer energy.

Ithink the answer is fusion 

Stars are born within the clouds of dust and scattered throughout most galaxies. a familiar example of such as a dust cloud is the orion nebula. turbulence deep within these clouds gives rise to knots with sufficient mass that the gas and dust can begin to collapse under its own gravitational attraction. as the cloud collapses, the material at the center begins to heat up. known as a protostar, it is this hot core at the heart of the collapsing cloud that will one day become a star. three-dimensional computer models of star formation predict that the spinning clouds of collapsing gas and dust may break up into two or three blobs; this would explain why the majority the stars in the milky way are paired or in groups of multiple stars.therefor, i would say the answer is: dust and gases contract.i hope this ! < 3

Is c