Which of the following are halide ores ?
A. Siderite
B. Cryolite
C. Fluorspar
D. Iron pyrite

Hint: As we know that ores are naturally occurring rocks that contain metals or metal compounds in sufficient amounts to make it worthwhile extracting them . Therefore in the above question we have to find which are the ores which contain halogens in them .

Complete step by step answer:
Let us examine each ore given in the question .
Siderite - The chemical formula of siderite is $FeC{O_3}$ . This ore is used to extract iron , it is not a halide ore as it does not contain any halogen .
Cryolite - The chemical formula of cryolite is $N{a_3}Al{F_6}$ . This is a halide ore as it contains fluorine which is a halogen . It is used for extracting fluorine .
Fluorspar - The chemical formula of fluorspar is $Ca{F_2}$ . It is also a halide ore used for extracting fluorine .
Iron pyrite - The chemical formula of iron pyrite is $Fe{S_2}$ . It is not a halide ore since it does not contain any halogen . Instead it is an ore used to extract sulphur .

Note:
Halogens are highly reactive elements and hence do not occur in the free state or native state . They mainly occur in the combined state in form of their halide salts( in ores ) although iodine occurs as iodate .