Pls answer

which of the following statements correctly describes a transformer?

a) transformers use steady magnetic fields to induce an end in a secondary loop
b) the more could in the solenoid of the primary loop of a transformer will induce a greater emf in the secondary loop.
c) transformers are used to keep the emf constant throughout a circuit.
d) the transformer in a car engine reduces the end in the secondary coil so as not to cause a fire during start up.