Autothermal reforming is one of the hydrogen production methods, which of the following statement is correct? $($Select all correct answers$)(15$p$)$

a$.$ It is a process that feeds both steam and oxidant with the fuel into the reactor.

b$.$ It requires complex heat managements due to the process complexity.

c$.$ It combines the endothermic steam reforming reaction and the exothermic partial oxidation reaction, so no external heat is required.

d$.$ This process can be carried out without a catalyst.