A fraction is said to be in lowest terms when:

A fraction is considered to be in lowest terms when there are no common factors, other than 1, that can divide both the numerator and the denominator evenly. This means that the greatest common divisor (GCD) of the numerator and the denominator is 1, indicating that they have been reduced to their simplest form. When a fraction is in lowest terms, it cannot be simplified further, making it easier to work with in calculations and providing clarity in representation.

Choosing the second option reflects this fundamental principle of fractions. The other options do not specifically address the condition of a fraction being in lowest terms and focus on unrelated characteristics. For example, discussing common factors or the relationship between the numerator and denominator does not pertain directly to achieving lowest terms. Understanding this concept is essential in various applications of mathematics, including operations involving fractions, simplifying algebraic expressions, and solving equations involving rational numbers.