Final answer:
The negative kaon (K-) is composed of a down quark and a strange antiquark, resulting in a net charge of -1. Its properties, including its spin and strangeness, are consistent with this quark configuration.
Step-by-step explanation:
The quark structure of a negative kaon (K-) consists of a down quark and a strange antiquark. Given the charges of a down quark (q = -1/3) and a strange antiquark (q = +1/3), the net charge of the kaon is -1, which aligns with the known charge of a negative kaon. Like other mesons, which are hadrons made up of a quark and antiquark pair, the negative kaon's properties, including its spin and strangeness, are a direct result of its quark content. Mesons, by definition, have integral charges due to the pairing of quarks and antiquarks with charges of +2/3 or -1/3 and +1/3 or -2/3, respectively. Furthermore, the quantum property known as color must be neutral (or "white") in hadrons, which is also true for the negative kaon, as for all mesons and baryons.