To solve this problem, we need to understand the concept of bond enthalpy for the $C-X$ bonds, where $X$ is a halogen.$\newline$Bond enthalpy is the energy required to break one mole of a bond in a gaseous molecule.$\newline$The bond enthalpy generally decreases as the size of the halogen increases. This is because larger halogens form longer and weaker bonds with carbon.$\newline$Let's analyze the $C-X$ bonds in the given options:$\newline$• $$CH$_3$-F: Fluorine is the smallest halogen, leading to a short and strong $C-F$ bond.$\newline$• $$CH$_3$-Cl: Chlorine is larger than fluorine, resulting in a longer and weaker $C-Cl$ bond compared to $C-F. \newline$• $$CH$_3$-Br: Bromine is larger than chlorine, resulting in an even longer and weaker $C-Br$ bond.$\newline$• $$CH$_3$-I: Iodine is the largest halogen, leading to the longest and weakest $C-I$ bond.$\newline$Therefore, the correct sequence of bond enthalpy from strongest to weakest is:$\newline$CH$_3$-F$>$CH$_3$-Cl$>$CH$_3$-Br$>$CH$_3$-I$\newline$This corresponds to Option 2.