Metal hydrides are ionic, covalent or molecular in nature. Among LiH, NaH, KH, RbH , CsH, the correct order of increasing ionic character is
A. `LiH gt NaH gt CsH gt KH gt RbH`
B. `LiH lt NaH lt KH lt RbH lt CsH`
C. `RbH gt CsH gt NaH gt KH gt LiH`
D. `NaH gt CsH gt RbH gt LiH gt KH`