Step 1: Understand the map scale ratio. A map scale of $1:100,000$ means that $1$ unit of distance on the map represents $100,000$ units of the same distance on the ground. Step 2: Apply the scale to a specific unit, such as centimeters. If $1$ cm on the map is chosen as the unit, then it represents $100,000$ cm on the ground. Step 3: Convert the ground distance from centimeters to more practical units like meters or kilometers. We know that $1$ meter (m) = $100$ centimeters (cm). So, $100,000$ cm = $\frac{100,000}{100}$ m = $1,000$ m. We also know that $1$ kilometer (km) = $1,000$ meters (m). So, $1,000$ m = $\frac{1,000}{1,000}$ km = $1$ km. Step 4: Compare the calculated ground distance with the given options. The calculation shows that $1$ cm on the map represents $1$ km on the ground. A. $1$ cm on the map represents $100$ m on the ground. (Incorrect) B. $1$ cm on the map represents $1$ km on the ground. (Correct) C. $1$ cm on the map represents $10$ km on the ground. (Incorrect) D. $1$ cm on the map represents $100$ km on the ground. (Incorrect) The correct option is B. The final answer is $\boxed{\text{B}}$ Send me the next one 📸