Final answer:
About 50% of commonly used herbal supplements have been deemed unsafe for use by pregnant women.
Step-by-step explanation:
The correct answer is (C) 50%. About 50% of commonly used herbal supplements have been deemed unsafe for use by pregnant women. It's important for pregnant women to be cautious about taking herbal supplements, as some may contain ingredients that could potentially harm the developing fetus. It's always advised to consult with a healthcare professional before taking any herbal supplements during pregnancy.