Before my work on the writer appeared there were many vague ideas afloat about him.

Answer: Option A

Circulating : move continuously or freely through a closed system or area.
Prevalent : widespread in a particular area or at a particular time.
Stagnant : (of a body of water or the atmosphere of a confined space) having no current or flow and often having an unpleasant smell as a consequence.
Primitive : relating to, denoting, or preserving the character of an early stage in the evolutionary or historical development of something.
Afloat : in general circulation; current.

Synonym of Afloat is Circulating