Read each sentence and decide whether the underlined portion contains a mistake. If it does, identify the best way to correct or improve the sentence by choosing the appropriate alternative from the answer choices. If the underlined portion requires no correction or improvement, choose No improvement or correction is required.

My dad is visiting his sister, which moved to Utah.


who moved to Utah.


that moved to Utah.


what moved to Utah.


whence moved to Utah.

No improvement or correction is required.