Correct option is (iv) Primary coil is made up of a very thick copper wire.
Correct statement is option (iv) as Primary coil made of Thick Coper wire has very less R. Therefore negligible power loss. Rest all options are reasons for power losses in a transformer.
Power loss happens due to Eddy current, Flux loss and Hysteresis. But in a transformer, the primary coil is made up of a very thick copper which has very less resistance and therefore negligible power loss due to heat.