How many letters does the top answer for “living or active in the absence of free oxygen” have?

The most common answer is anaerobic (9 letters).

Crossword clue: living or active in the absence of free oxygen

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

anaerobic 9 letters wn-def

living or active in the absence of free oxygen

anaerobiotic 12 letters wn-def

living or active in the absence of free oxygen