Which of the following facts is directly explained by the statement '$O$ is a smaller atom than $S$?'

• A
  $H_2O$ boils at a much higher temperature than $H_2S$
• B
  $H_2O$ undergoes intermolecular hydrogen bonding
• C
  $H_2O$ is liquid and $H_2S$ is gas at room temperature
• D
  $S-H$ bond is longer than $O-H$ bond