The composition of a syrup is
variable
The explanation for the correct answer - (A) Variable
The syrup is a mixture.
Mixture - When two or more substances are mixed physically in any random proportion in such a way that they retain their individual properties is called a mixture.
The explanation for the incorrect answers -
(B) Fixed - if we mix two substances in fixed composition then the product obtained will be called a compound.
(C) Both (a) and (b) - since sugar syrup is a mixture therefore both options cannot be correct.
Hence, option (A) is correct. The composition of syrup is variable.