Carbon dioxide would be classified as:

a an element
b a compound
c a heterogeneous mixture
d a solution

The correct answer is option B, that is, a compound.  

A substance, which is formed of two or more different elements is known as a compound. Carbon dioxide refers to a compound, comprising of three molecules that are made up of two elements, chemically combined with each other, that is, one carbon atom and two oxygen atoms. It is a chemical compound generally in the form of a gas.  

the right side of the picture going down is:

polymerase

protein

transport vesicle

modified protein

the left side of the picture going down is:

dna helix

single-stranded rna

endoplasmic reticulum

ribosome

golgi apparatus

protein released from vesicle

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not too sure but maybe in the hot springs.