Option A is correct answer.
According to octet rule, atoms have tendency to lose, gain and share electrons to complete its octet i.e. eight valence electrons are surrounded to the atom.
Since, sulphur contains six valence electrons and two chlorine atoms are present in the reaction having seven valence electrons. Thus, to complete their octet, chlorine shares a pair of electrons with the sulphur atom.
I believe c is the right answer.
