Answer: B) FALSE Explanation: False. The ankle is not the third-class lever in the body.   Levers are typically labeled as first class, second class, or third class. All three types are found in the body, but most levers in the human body are third class. First-class levers in the human body are rare and have the axis (fulcrum) located between the weight (resistance) and the force. One example is the joint between the head and the first vertebra. In a second-class lever, the weight (resistance) is located between the axis (fulcrum) and the force. An example of a second-class lever in the human body is found in the lower leg when someone stands on tiptoes In a third-class lever, the most common in the human body, force is applied between the resistance (weight) and the axis (fulcrum). There are numerous third-class levers in the human body; one example can be illustrated in the elbow joint.

Answer: D) along a production possibilities curve, increases in the production of one good require larger and larger sacrifices of the other good Explanation: Opportunity cost is the cost of what you are giving up to do what you are currently doing. If you can either go to work or go to the beach, and you choose to work, the opportunity cost of working is the value you would have gotten had you gone to the beach.   The law of increasing opportunity costs states that as you increase production of one good, the opportunity cost to produce an additional good will increase.

Answer: A) Limestone Explanation: Karst is a type of landscape that is characterized by caverns, caves, sinkholes, and underground streams. These features were all caused by erosion of the underlying rock.   Limestone type of rock usually underlies a karst landscape.