Let’s analyze each option to find out which one are correct

Options (i) suggests that cationic detergents have germicidal properties which is true. (Germicidal properties means that the germs are being killed and terminated by the cationic detergents.)

Option (ii) says that bacteria can degrade the highly branched chains which is false. It’s easier to degrade straight chains by the bacteria

Option (iii) is correct as some synthetic detergents can give foam in ice cold water. For example, Cetyltrimethyl ammonium bromide, Sodium 4-(1-dodecy) benzenesulphonate (SDS) etc.

Option(iv) comments that synthetic detergents are not soaps which is true. They do have all the properties of soaps but is not actually soap.

Hence options (i) and (iv) are the correct options. Options (ii) and (iii) are incorrect.