A young researcher wants to test how well extremophiles, organisms that thrive in extreme conditions, live in different environments. She will do this by putting extremophiles of different species into different solvents. Because of limited lab space, she can run only one sample at a time, and each sample must remain undisturbed for 7 days. To reduce the total time needed to process all samples, the researcher decides to use two acidic solutions along with a control. The information below includes the extremophiles and the solvents the researcher will use in her tests.

\begin{tabular}{|c|}
\hline \begin{tabular}{l}
Species of \\
Extremophiles
\end{tabular} \\
\hline T. prosperus \\
\hline A. aceti \\
\hline A. brierleyi \\
\hline H. acidophilum \\
\hline
\end{tabular}

\begin{tabular}{|l|c|}
\hline \multicolumn{1}{|c|}{ Name } & [tex]$pH$[/tex] \\
\hline hydrochloric acid & 1.3 \\
\hline ascorbic acid & 4.2 \\
\hline water & 7.0 \\
\hline
\end{tabular}

Based on the tables, how many days will all of the researcher's experiments take? You may use the calculator.

A. 7
B. 21
C. 49
D. 84