Atomic size

a. decreases as you move from top to bottom within a group

b. remains constant within a period

c. decreases as you move from left to right across a period

d. increases as you move from left to right across a period

Option C, decreases as you move from left to right across a period

As you move from left to right across a period, the atoms get more and more protons. These protons pull on the electrons, making the atoms progressively smaller and smaller because of the increasing pull.

hey your not cool]      

atomic number of carbon is 6

electronic configuration of carbon is 1s²2s²2p²

orbital diagram of c is as shown here in the image.