please answer quickly and clearly. ill upvote right away! please answer all parts. thank you!

While converting an infix expression to postfix using stack, if a left parenthesis is encountered what should we do? compare it with the element on the top of the stack O ignore it pop it from the stack O push it on the stack What is the Big-O notation for T(n)? T (n) = 3n + 6 (lg n) +9 (n lg n) + n! O O(n) O O(n!) O O(logn) O O(nlogn)