Many phase I studies now include adaptive study designs which allow changes to the design of the trial as new information is discovered; as is often the case with phase I studies. According to the author, adaptive trial designs have many benefits, including:

i don't get what you mean

explanation:

answer; ///first they would cross the atlantic ocean, and end up either in europe or africa; good luck

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."