Elements near the noble gases tend to form bonds.

a. ionic
b. covalent
c. metallic

ionic bond

Explanation:

Noble gases have complete octet. The elements near to noble gases gain electrons and get stable electronic configuration by completing the octet.

Consider the example of halogen element:

Ionic bond:

It is the bond which is formed by the transfer of electron from one atom to the atom of another element.  

Both bonded atoms have very large electronegativity difference. The atom with large electronegativity value accept the electron from other with smaller value of electronegativity .

For example:

Sodium chloride is ionic compound. The electronegativity of chlorine is 3.16 and for sodium is 0.93. There is large difference is present. That's why electron from sodium is transfer to the chlorine. Sodium becomes positive and chlorine becomes negative ion.  Chlorine have seven valance electrons and sodium have one valance electron. To complete the octet sodium lose its one electron and chlorine accept one electron and form ionic compound.

- both b and d.

-since b and d are the closest coastlines then that makes it the most affected.

< 3

the answer is b. dilution