When two or more substances combine, but each keeps its own properties, the new combination is called a(an)
a) element
b) mixture
c) compound
d) homogeneous substance

The correct answer is option B) Mixture.

Explanation:

When two or more substances are mixed but they do not lose their properties then we are in the presence of a mixture.

An example of this is the air we breathe, where many gases are mixed but not chemically combined.

That is why a mixture differs from a chemical compound, where substances can change their chemical composition when mixed.

Given this information we can say that the correct answer is option B.

c. heat from the poles back down towards the equator.