Which of the Following Statements Is an Overall Summary of the Findings

Which of the following statements is an overall summary of the findings from the Viking biology experiments?

A) the Martial soil showed no signs of chemical or biological activity
B) the Martian soil showed clear signs of biological activity
C) the Martian soil was chemically reactive but showed no conclusive signs of biological activity
D) the Martian soil contained organic molecules but showed no signs of biological activity