Consider the following algorithm:

Algorithm insertDbl $($list$,$ dataIn$)$

This algorithm inserts data into a doubly linked list.

Pre list is metadata structure to a valid list dataIn contains the data to be inserted

Post The data have been inserted in sequence

Return $0$: failed$--$dynamic memory overflow

$1$: successful

$2$: failed$--$duplicate key presented

if $($full list$)$

return $0$

end if

set found to searchList $($list$,$ predecessor, successor, dataIn key$)$

if $($not found$)$

allocate new node

move dataIn to new node

if $($predecessor is null$)$

set new node back pointer to null

set new node fore pointer to list head

set list head to new node

else

set new node fore pointer to predecessor fore pointer

set new node back pointer to predecessor

end if

if $($predecessor fore null$)$

set list rear to new node

else

set successor back to new node

end if

set predecessor fore to new node

return $1$

end if

return $2$

endinsertDbl

What does the condition $"$if $($predecessor fore null$)"$ test for?

Question $49$Select one:

a$.$

insertion at end of list

b$.$

insertion in an empty list

c$.$

insertion at beginning of list

d$.$

insertion in a null list