Which statement is true regarding blood transfusions? Blood transfusions were common practice in the seventeenth century. They routinely infused human blood into animals. Blood transfusions were performed by infusing sheep's blood into humans; in the eighteenth century, they were common and highly successful. In the seventeenth century, blood transfusions were rarely done and often fatal; they were outlawed until the nineteenth century. A blood transfusion is a lifesaving procedure that was developed and perfected in the nineteenth century.

 In the seventeenth century, blood transfusions were rarely done and often fatal; they were outlawed until the nineteenth century.

Explanation:

In the 17th century, people began to speculate that blood transfusions could be done to save human lives especially after it was discovered that blood flowed forward not back and forth.

They used animal blood for transfusion however which resulted in it being fatal most times. This led to several governments in Europe issuing bans on blood transfusion and therefore making it illegal until the process dramatically improved in the 19th century.