1. The problem asks to classify the number 0 among the given options: (a) positive integer, (b) rational number, (c) singular, (d) binary set. 2. Let's analyze each option: - (a) Positive integer: Positive integers are numbers greater than zero (1, 2, 3, ...). Since 0 is not greater than zero, it is not a positive integer. - (b) Rational number: A rational number is any number that can be expressed as $\frac{p}{q}$ where $p$ and $q$ are integers and $q \neq 0$. Since $0 = \frac{0}{1}$, 0 is a rational number. - (c) Singular: This term is ambiguous here, but in mathematics, "singular" often refers to matrices or points where certain properties fail. 0 itself is not singular in this context. - (d) Binary set: The binary set usually refers to the set $\{0,1\}$. While 0 is an element of the binary set, the question asks if 0 "is" the binary set, which it is not. 3. Therefore, the correct classification is that 0 is a rational number. Final answer: 0 is a rational number (option b).