The answer is dilute. A dilute salt solution contains a small amount of salt with high water concentration while a concentrated salt solution has a large amount of salt with a lower water concentration. Salt is inorganic hence it is not monounsaturated, which is a term related to organic compounds. The salt is unable to dissolve anymore in a saturated salt solution, leaving the undissolved salt at the bottom and this is not the case here since we only have a small amount of salt.