A proportion is an equation that states two ratios are equal. To determine which option is a proportion, we can check if the two fractions on each side of the equation are equivalent.
Option 1: \[ \frac{5}{6} = \frac{15}{18} \] To check if these fractions are equal, we can cross-multiply: \[ 5 \times 18 = 90 \quad \text{and} \quad 6 \times 15 = 90 \] Since both products are equal, \(\frac{5}{6} = \frac{15}{18}\) is true, making Option 1 a proportion.
Option 2: \[ \frac{5}{6} = \frac{20}{18} \] Again, we can cross-multiply: \[ 5 \times 18 = 90 \quad \text{and} \quad 6 \times 20 = 120 \] Since \(90 \neq 120\), \(\frac{5}{6} = \frac{20}{18}\) is false, so Option 2 is not a proportion.
Thus, Option 1 is the correct answer: it is a proportion.