Answer:
sexual chromosome linked characteristics
Explanation:
The sexual crhomosomes are XX (for females) and XY (for males).
The Y chromosome have less genes than the x, because of this, some characteristics are expressed at males and not at females.
Males has only one copy of the gen, carried by the only X chromosome (in this case, the leght of the tail). Nevertheless the females have two copies of the gen, (short and long tail).
So, the fenotype resulting is a dominant characterisitic related to x chomosome (long tail).