The table shows physiological data collected from an athlete during a training session.
\begin{array}{|c|c|c|c|}
\hline \textbf{Time} & \textbf{Heart Rate} & \textbf{Stroke Volume} & \textbf{Cardiac Output} \\
\textbf{(minutes)} & \textbf{(bpm)} & \textbf{(mL)} & \textbf{(L/min)} \\
\hline 0 \text{ (at rest)} & 70 & 70 & 4.9 \\
\hline 5 & 120 & 100 & 12.0 \\
\hline 10 & 150 & 110 & 16.5 \\
\hline 15 &160 & 110 & 17.6 \\
\hline \end{array}
Which statement best explains the relationship between these physiological responses during training?
- Heart rate and stroke volume decrease at the same rate during exercise
- Cardiac output increases mainly due to increases in stroke volume
- Heart rate continues to increase throughout exercise while stroke volume plateaus
- Cardiac output decreases as heart rate increases during training