The correct answer is B. Biyu. The question is asking how many nouns are in the sentence. The sentence "Audu ya hau keke sabo jiya" contains two nouns: "Audu" (a person's name) and "keke" (a bicycle). Therefore, the correct answer is B. Biyu (two). Note that "sabo" is an adjective modifying the noun "keke", and "jiya" is an adverb indicating the time of the action, so they are not counted as nouns.