inorganic chemistry - Melting points of alkali metal halides

The correct order of melting point of alkali metal halides is:

1. $\ce{MF}>\ce{MCl}>\ce{MBr}>\ce{MI}$


2. $\ce{MI}>\ce{MBr}>\ce{MCl}>\ce{MF}$


3. $\ce{MCl}>\ce{MF}>\ce{MBr}>\ce{MI}$


4. $\ce{MI}>\ce{MF}>\ce{MCl}>\ce{MBr}$

The correct answer to this is option (1), the reason I could think of is that as the size of anion in ionic compound increases the covalent character increases and hence the melting point decreases.