An organic compound (A) reacts with PCI, to give the compound (B), which on dehydrohalogenation with alcoholic NaOH gives the compound (C). The compound (C), upon ozonolysis gives the compound (D). When compound (D) is treated with aqueous NaOH, mixture of sodium methanoate and methanol is obtained. Identify the compounds A, B, C and D with reactions involved. What happens when the compound (A) is warmed with iodine and sodium hydroxide? ​