What is the purpose of the highlighted line?

bool push $($T item$)\{$ node $*$temp $=$ new node$($item$)$; if $($temp $==0)$ return $0$; $//<--$ Focus on this line $//...($rest of the push function$)$

$\}$

a$.$ To check if memory allocation was successful

b$.$ To initialize the data of the new node

c$.$ To add the new node to the top of the stack

d$.$ To allocate memory for a new node