Melamine

Polymers are made up of small molecules called monomers. Polymers which are formed by one type of monomer called homopolymers and which are formed by more than one type of monomers are called co-polymers. Natural polymers are biodegradable whereas systhetic polymers may or may not be. Addition or chain growth polymerization involves the repeated addition of monomers to the polymer chain. The monomers are unsaturated compounds and this type of polymerization takes placed by ionic (cationic or anionic) as well as free radical a series of condensation reactions between the monomers. Each monomer normally contains two functional groups. Branch chain polymers may be condensation polymers or addition but cross linked polymers are always condensation polymers. Total number of lone pairs of electrons in melamine is:

Recently a large number of children/ infants have fallen sick because of the use of melamine contaminated dairy products in the world. Due to this many countries like South Africa, Japan, and Singapore etc. have stopped import of these products. Which of the following countries was the main exporter of such products ?