The substance that will be flattened on beating with a hammer is (d) zinc granule.
Explanation: Zinc is a metal, and metals are known for their malleability, meaning they can be beaten into thin sheets without breaking.
Why other options are incorrect:
(a) crystal of iodine: Iodine is a non-metal, and non-metals are typically brittle and break when hammered.
(b) lump of sulphur: Sulphur is also a non-metal and will crumble under pressure.
(c) piece of coal: Coal is a solid form of carbon, which is a non-metal. It will break apart rather than flatten when hammered.