Question

meteorites are divided into three main groups: iron, stony and ___.
a nickel
b metal
c silicate
d stony - iron

Explanation:

Meteorites are classified into three main groups: iron (mostly iron - nickel alloy), stony (silicate - rich), and stony - iron (a mix of silicate and metal). Nickel is a component of iron meteorites, metal is too broad, and silicate is related to stony meteorites. Stony - iron is the correct third group.

Answer:

D. stony - iron