Questions: What is the numerical value that reflects body weight adjusted for height and is used to assess risk for chronic health problems?

The answer is the second one: body mass index.

Explanation for each option:

1. Healthy People 2020 obesity index: This is not a standard term used to reflect body weight adjusted for height. Healthy People 2020 is a set of health objectives for the nation to achieve over a decade, but it does not specifically refer to a numerical value for assessing body weight and height.
2. Body mass index: This is the correct answer. Body mass index (BMI) is a numerical value calculated from a person's weight and height and is widely used to assess whether an individual has a healthy body weight for a given height. It is commonly used to assess the risk for chronic health problems such as obesity, heart disease, and diabetes.
3. Height/weight ratio tables: These tables provide a range of healthy weights for different heights but do not provide a single numerical value like BMI. They are less commonly used in modern health assessments compared to BMI.

Summary: The numerical value that reflects body weight adjusted for height and is used to assess risk for chronic health problems is the body mass index (BMI).