Answer: (2) chlorine
Expalanation: 1) Carbon is an element with atomic number 6 and thus has 6 electrons. It's electronic configuration is:

Carbon needs to lose or gain 4 electrons to attain noble gas configuration.
2) Chlorine is an element with atomic number 17 and thus has 17 electrons. It's electronic configuration is:

Chlorine needs to gain 1 electron to attain noble gas configuration and thus has strongest tendency to attract electrons in a chemical bond.
3) Silicon is an element with atomic number 14 and thus has 14 electrons. It's electronic configuration is:

Silicon needs to lose or gain 4 electrons to attain noble gas configuration.
4) Sulfur is an element with atomic number 16 and thus has 16 electrons. It's electronic configuration is:

Sulfur needs to gain 2 electrons to attain noble gas configuration.