All of the factors you listed can contribute to the covalent character of a compound. The extent to which each factor contributes depends on the specific compound and its chemical properties.
The polarising power of a cation refers to its ability to pull electron density towards itself, which can result in partial covalent bonding between the cation and the anion. Similarly, the polarisability of an anion refers to its ability to be distorted by an oppositely charged ion, which can lead to partial covalent bonding.
The distortion caused by a cation also contributes to covalent character, as it can lead to the formation of partial covalent bonds between the cation and anion.
Finally, the polarisability of a cation can also play a role in covalent character, as a highly polarisable cation can form partial covalent bonds with the anion due to the distortion it causes in the anion.
Therefore, all of these factors can contribute to the covalent character of a compound, and their relative importance depends on the specific compound and its chemical properties.
Answer. A, B, C