Strontium chloride has a fluorite structure, which of the following statement is true ?

1. The strontium ions are in a body-centered cubic arrangement

2. The strontium ions are in a face-centered cubic arrangement

3. each chloride ion is at the centre of a cube of 8 strontium ions

4. each strontium ion is at the centre of a tetrahedron of 4 chloride ions