b) is the ans
TsOH ABSTRACTS H+...O- ATTACHES ITSELF TO C OF CARBONYL GRP IN HCHO....WHILE THE O-OF HCHO ATTACHES TO C OF CH+-OH....FUTHER HEATING KICKS OUT OH...AND B IS WHAT U GET
@MKM: DUE TIME DEFICIT I CUD NOT PUT UP THE DIAGRAM...SRY FOR THAT....I LL DO THAT NEXT TIME