Final answer:
Medication categories A and B under FDA's pregnancy categories are considered safe for use in pregnancy, whereas categories C, D, and X have various risks that must be weighed. Ultrasounds are imaging studies safe to use during pregnancy. Therefore, the correct option is A, B.
Step-by-step explanation:
The categories of medications under the FDA's pregnancy categories considered to be within safe limits for use during pregnancy are Category A and Category B. Category A includes drugs which have been tested and found to be safe in controlled human studies, while category B signifies drugs that have not shown any harm to the fetus in animal studies and there are no adequate and well-controlled studies in pregnant women. However, Category C drugs should be given only if the potential benefit justifies the potential risk to the fetus, Category D drugs show positive evidence of human fetal risk but may be used in serious situations, and Category X drugs are contraindicated in pregnancy. To determine whether a drug is deemed to be suitable for administration to humans, an acceptable risk assessment must be completed. One such imaging study that is deemed safe and used widely for medical assessments during pregnancy is ultrasound, as it does not use ionizing radiation and thus presents no known harm to the fetus.