As part of a project, Thomas has developed two algorithms for solving key portions of the project. The algorithm for step A involves two nested loops and can be completed in approximately $3n^2-n$ steps, the algorithm for step B uses a divide and conquer strategy and can be completed in $2nlogn$ steps for an input sequence of size $n.$ If step $B$ always follows step $A,$ what is the time complexity of this portion of the project?

$O(nlogn)$

$O(n^2)$

$O(n^2+nlogn)$

$O(n^{3}logn)$