Rajesh designed an experiment to test the effect of fertilizer on plant growth. The table below shows the data he collected.

Which changes should Rajesh make to his experiment to improve the validity of the data? Check all that apply.

- Add twice as much fertilizer to the plants.
- Measure the growth of a plant that did not receive fertilizer.
- Perform additional trials.
- Remove plant 2.

\begin{tabular}{|c|c|c|}
\hline \begin{tabular}{c}
Plant \\
[tex]$\#$[/tex]
\end{tabular} & \begin{tabular}{c}
Fertilizer \\
[tex]$( mL )$[/tex]
\end{tabular} & \begin{tabular}{c}
Plant Growth \\
[tex]$( mm )$[/tex]
\end{tabular} \\
\hline 1 & 2.0 & 1.0 \\
\hline 2 & 3.0 & 1.5 \\
\hline 3 & 4.0 & 2.0 \\
\hline
\end{tabular}