In this channel of communication, messages are carried by sound and light waves.
a. teleconference
b. face-to-face
c. voicemail
d. hard copy memos

With these questions , 15 pts & brainliest

Which is not a step in the rock cycle?

Examine the equation. 23490th→23088ra+42he what kind of barrier would you need to block the radioactive particles from this reaction? a.a piece of paper b.a sheet of aluminum foil c. a two-inch block of lead d. a solid concrete block