Step 1: Recognize the behavior class.
Repetitive actions like {compulsive counting, checking, or washing} are compulsions aimed at reducing anxiety from intrusive obsessions.
Step 2: Differentiate from other disorders.
Schizophrenia involves thought disorder/psychosis; paranoia involves delusional themes—neither primarily features ritualistic counting.
Step 3: Conclude.
\[
\boxed{\text{Obsessive–compulsive neurosis (Option B).}}
\]