Mcq doubts - sorting

Assume that a merge sort algorithm in the worst case takes 30 seconds for an input of size 64. Which of the following most closely approximates the maximum input size of a problem that can be solved in 6 minutes?

256

512

1024

2048

@prerna_gupta31
(https://www.geeksforgeeks.org/gate-gate-cs-2015-set-3-question-37/)