The correct answer is:
As the mother of the Kings' two best players, I have to agree.
A bias means to be one-sided, lacking a neutral viewpoint. It´s a disproportionate weight in support of or opposite something, a person, or group faced with another, normally in a way deemed to be unfair. Biases can be acquired implicitly in certain cultural contexts, or such as in this case, develop due to private interests or closeness to on side or the other.