ANS:C - sulphuric acid

The unit molar solution of sulphuric acid (H2SO4) is the best conductor of electricity among the options provided. Sulphuric acid, when dissolved in water to form a unit molar solution, dissociates into ions, particularly hydrogen ions (H⁺) and sulphate ions (SO4^2-). These ions facilitate the conduction of electricity through the solution by carrying electric charge. Since sulphuric acid dissociates almost completely in solution, it produces a higher concentration of ions compared to other substances listed, making it the best conductor of electricity in this context. The other options, sodium chloride (NaCl), acetic acid (CH3COOH), and sucrose (C12H22O11), do not dissociate into as many ions in solution or do not ionize at all in the case of sucrose, resulting in lower conductivity compared to sulphuric acid.