Final answer:
The first-generation scanners were capable of imaging only the head/brain area. Ultrasound is considered the safest imaging modality during pregnancy as it does not involve radiation exposure.
Step-by-step explanation:
First-generation scanners were initially capable of imaging only the head/brain area, which means the correct answer to the question is a) head/brain. As medical imaging technology evolved, types of CT scanners expanded their capabilities to include detailed views of various parts of the human body. Concerning the safest imaging study during pregnancy, ultrasound is considered the least invasive and does not use harmful electromagnetic radiation, making it the most suitable option (c). CT scans, despite their detail and usefulness, expose patients to higher doses of radiation compared to standard X-rays, hence are not preferred for pregnant women unless absolutely necessary.