Among LiCl, RbCl, BeCl₂ and MgCl₂ the compounds with the greatest and least ionic character respectively are

As the size of the cation increases ionic character increases, so among the given chlorides the Rb is having larger size and the element having least size is Be. So, the compound having more ionic character is RbCl. The compound having least ionic character is BeCl₂

​Hence option B is correct.