Answer: Option D
Explanation: In simple words, normal cash flows refers to those cash flows which have one initial investment at the beginning followed by a stream of inflows while in case of non normal cash flows the stream keeps changing from inflows to outflows.
Normal cash flows have only one IRR as there can only be single rate at which NPV will be zero while in case of Non normal there are two IRR due to uneven stream.
Thus, we can conclude that the correct option is D.