Huh? need help i do not understand this

It is called a neutralization reaction

It is a mixture. simply put, a compound must be pure, that is, of only one chemical structure and composition. a mixture is made of different chemical substances (i.e. elements, molecules, compounds) that are not chemically bonded to each other, but instead physically grouped together, as in the case of gasoline (a homogeneous solution).

Ibelieve it is b. proton.hope my answer has you : )