Help please! ACTH question right before test

Yes I am taking my test VERY shortly. I just got a question on UWorld that states ACTH is what directly causes skin pigmentation even if it is secreted ectopically (i.e. small cell lung cancer). However, I had always learned that only ACTH secreted from the pituitary can cause this because it is the splitting of POMC that also releases ACTH and that was one way you could differentiate b/w pituitary ACTH and ectopic ACTH secretion.

Please somebody tell me which it is because it is test time in a few hours. Thank you so much