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