In choosing a compound to serve as internal standard (IS) for a GC analysis, which of the following are desirable properties to look for?

A) The compound is one that is already present in the sample to be analyzed.
B) The compound is one that is not already present in the sample.
C) The compound is very different in structure and chemical properties to the analyte species.
D) The compound is somewhat similar in structure and chemical properties to the analyte species.
E) The compound is exactly the same as the analyte.