In $\textit{Neurospora crassa}$, a mutation in the $\textit{poky}$ gene results in a slow growth phenotype (poky). The results of four crosses are given below.
- wild-type $ ♀ \times$ wild-type $ ♂ \rightarrow$ All progeny are wild-type
- wild-type $ ♀ \times$ poky $ ♂ \rightarrow$ All progeny are wild-type
- poky $ ♀ \times$ wild-type $ ♂ \rightarrow$ All progeny are poky
- poky $ ♀ \times$ poky $ ♂ \rightarrow$ All progeny are poky
Which one of the following explains the inheritance mode of poky?
- Episomal inheritance
- Mendelian inheritance
- Mitochondrial inheritance
- X-linked inheritance