Compound (A) (molecular formula C3H8O) is treated with acidified potassium dichromate to form a product B (molecular formula C3H6O). 'B' forms a shining silver mirror on warming with ammoniacal silver nirate. 'B' when treated with an aqueous solution of H2NCONHNH2⋅HCl and sodium acetate gives a product 'C'. Identify the structure of 'C':