General principle of solubility is 'like dissolves like'
[tex] CaBr_{2} [/tex] is an ionic compound, wherein the constituent ions ([tex] Ca^{2+} [/tex] and [tex] Br^{-} [/tex]) are held by electrostatic forces of interaction.
Such ionic compounds are soluble in polar solvents.
Among the solvent mentioned in question, water ([tex] H_{2}O [/tex]) has maximum polarity. Hence, [tex] CaBr_{2} [/tex] is most likely to dissolve in [tex] H_{2}O [/tex]
