Final answer:
The type of inheritance in which offspring inherit their phenotype directly from the mother's genotype is cytoplasmic inheritance, due to the maternal transmission of organelles like mitochondria.
Step-by-step explanation:
In the context of the question, the type of inheritance in which the phenotype of the offspring is determined directly by the genotype of the mother is known as cytoplasmic inheritance. This occurs because certain organelles, like mitochondria (which have their own DNA), are inherited exclusively from the mother. So, traits encoded by mitochondrial DNA are passed on from the mother to all her offspring regardless of their sex. In contrast, sex-linked inheritance refers to traits associated with genes located on the sex chromosomes. However, sex-linked traits are typically inherited from both parents but expressed differently in males and females due to differences in the X and Y chromosomes.