Ethanol is a/an a. organic acid. b. substituted hydrocarbon. c. aromatic hydrocarbon. d. carbohydrate.

Ethanol is a substituted hydrocarbon. The "ol" suffix used in ethanol is for the functional group -OH, or alochol group. When any functional group is attached to a pure hydrocarbon, that hydrocarbon shows properties of that functional group. 
For ethane as well, which have molecular formula of C2H6, when one hydrogen is substituted by one -OH group it becomes C2H5OH which we call as ethanol or ethyl alcohol. If two hydrogen are substituted, it becomes -diol and as such.
There are number of ways to prepare ethanol by pure hydrocarbon. Generally ethanol can be prepared by fermentation of starch and molasses. Also various organic reaction gives ethanol as product. When ethene is  reacted with steam catalysed by phosphoric acid.

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