Given the following steps necessary to insert an item into a doubly linked list, order these in the order that they must be executed.

$1.$ Set Next$($newNode$)$ to location

$2.$ Set Back$($location$)$ to newNode

$3.$ Set Next$($Back$($location$))$ to newNode $4.$ Set Back$($newNode$)$ to Back$($location$)$

a$)1,2,3,4$

b$)2,3,1,4$

c$)4,1,3,2$

d$)4,3,2,1$