To determine the correct order of basic strength of methyl-substituted amines in aqueous solution, we need to consider several factors:$\newline$1. The basicity of amines is influenced by the availability of the lone pair of electrons on the nitrogen atom.$\newline$2. Alkyl groups, such as methyl groups, are electron-releasing and increase the electron density on nitrogen, enhancing basicity.$\newline$3. In aqueous solution, solvation effects also play a significant role. Solvation stabilizes the conjugate acid formed by protonation of the amine.$\newline$Let's analyze the given amines:$\newline$• $CH_3NH_2$