The correct answer is option 1: 72-80. In a normal adult human, the average resting heart rate is between 60-100 beats per minute. However, the most common range is generally considered to be 72-80 beats per minute.

Option 2: 70-75 is close to the correct answer and falls within the normal range of heart rate for a healthy adult.

Option 3: 80-97 is also within the normal range, although it is slightly higher than the commonly accepted average range.

Option 4: 82-87 is also within the normal range, but it is slightly higher than the average range.

It is important to note that heart rate can vary depending on factors such as age, fitness level, and overall health. Additionally, during physical activity or periods of stress, the heart rate may increase.