Mixtures of oven cleaners and household bleach release chlorine, and mixtures of bathtub cleaners and household bleach release chlorine. However, a mixture of ordinary soap and household bleach does not release any gas. When cleaning agents are added to household bleach, no chlorine gas is released. So which of the following can we think about this unknown cleaning agent? ['It is ordinary soap.', 'Neither oven cleaner nor bathtub cleaner.', 'It contains ordinary soap ingredients, as well as oven cleaner or bathtub cleaner ingredients.', 'It contains ordinary soap ingredients, but does not contain oven cleaner and bathtub cleaner ingredients.']