Answer:
The revision of the passage that best connects ideas and adds variety is - Running is inexpensive, yet you can run on a treadmill. You can run outdoors, however, you should not run on icy roads.
Explanation:
The sentences given are short and simple. But when it comes to fusing the meaning and making it sound better, linking words are used. Here, using the words "yet" and "however" all the short sentences are joined to form one sentence which sounds well and offers the correct meaning at the same time. The flow of the sentence is better. There is less amount of jarring and stopping which helps it to connect ideas and add variety to the joined sentences.
Skin immunity is a property of skin that allows it to resist infections from pathogens. In addition to providing a passive physical barrier against infection, the skin also contains elements of the innate and adaptive immune systems which allows it to actively fight infections. I hope that this helps.
The correct answer is D. Your muscles are burning. If you are experiencing any of the other 3 choices, either you probably have asthma, or you just held your breath during sprints.
