Synthetic compounds found in an organism but not normally produced or expected to be present in that organism are called
pesticides
bioremediators
recalcitrant compounds
xenobiotics

The correct answer is D. Xenobiotics

Explanation:

In biology, the word "xenobiotics" refers to any substance or chemical compound that is considered as not natural or synthetic is an organism, this means the substance or compound is not produced by the organism and therefore it is not expected to be found on it. In the seam way, a substance that is natural to the organism but that is found in abnormal concentration might be considered as a xenobiotics. This concept differs from pesticides because these are substances used to control pests and from bio remediators because these are used to deal with contamination. Therefore, the word that describes synthetic compounds that are not produced or expected to be present in an organism is xenobiotics.