Two chemical substances X and Y combine together to form a product P which contains both X and Y. $\text{X}+\text{Y}\to \text{P}$

X and Y cannot be broken down into simpler substances by simple chemical reactions.  Which of the following statements concerning X, Y and P are correct ?

i) P is a compound                     ii) X and Y are compounds

iii) X and Y are elements          iv) P has a fixed composition