、。
It's hard to choose what's right and what's wrong, but you have to choose.
Literal
What [subject-が] correct [connective-くて] what [subject-が] wrong [question-か] choosing [topic-は] difficult [but-が], must-choose.
A philosophical statement about moral choice. 何が正しくて何が間違いか ('what is right and what is wrong') embeds two parallel questions joined by the い-adjective connective ~くて. 選択するのは難しい uses the nominalized verb (の) as the topic of 難しい. しなければならない ('must do') is the formal obligation pattern: ~なければならない. The contrastive が ('but') sets up the tension: choosing is hard, yet unavoidable.