Q. Xenobiotics which are inherently resistant to microbial attack are called as

Explanation by: Official MCQ Buddy

Xenobiotics that are inherently resistant to microbial degradation are called recalcitrant compounds. These substances do not break down easily in the environment due to their complex chemical structures, stability, or lack of microbial enzymes capable of degrading them.
Persistent compounds (Option A) remain in the environment for a long time but are not necessarily completely resistant to microbial attack.
Biodegradable (Option C) compounds can be broken down by microorganisms, which is the opposite of recalcitrant.
All of the given options (Option D) is incorrect since not all options describe xenobiotics resistant to microbial attack.