skeletal system and the muscular system,
Muscles are attached to the skeleton and work assuming that the skeleton is there; for example, there is no muscle that makes sure you don't bend the middle of your arm, as it's stable because there is a bone in it. Basically, the skeleton is a scaffolding for the muscles.
the skeletal system and the nervous system,
Many nerves run along the skeleton, or even inside the bones, and the bones protect the nerves; for example in the spinal cord
the muscular system and the nervous system.
The Nervous system controls the muscles; it sends the muscles commands
The second option which says "Dr. Lee is using an electron microscope; Dr. Murphy is using a light microscope" is the correct option. This is because unlike electron microscopy that show cell organelles in details, <span>most organelles are not clearly visible by </span><span>light microscopy.</span>
Long-term activation of your body’s stress response system, along with prolonged exposure to cortisol and other stress hormones, puts you at risk for health troubles. These health issues include digestive problems, anxiety, headaches, depression, sleep problems, weight gain, memory and concentration issues, high blood pressure, heart disease and strokes. Being stressed also lowers your threshold for pain, causing more extreme discomfort from the previous affects.
It would be D. because nothing can be 100% you can still get pregnant from all of those things.
hope i helped! :) <span />