Which observation tool allows shaunas doctor to monitor her blood circulation in real time?

The right answer is ultrasound.

Ultrasound is an imaging technique that uses ultrasound. It is used routinely in human and veterinary medicine, but can also be used in research and industry.

Contrast ultrasound is one that uses a contrast medium. The contrast medium composed of microbubbles is injected into the bloodstream intravenously at the time of the ultrasound examination of the patient. The microbubbles of the contrast medium are highly reflective to ultrasound during ultrasound examination; thus making it possible to image the blood vascularization of the organs for diagnostic purposes.

substitution is the answer in this case

its b. greenhouse gasses trap uv rays for heat so that the plants stay alive.