A student connects a battery of electromotive force (emf) \(\varepsilon\) and internal resistance \(r\) to a variable resistor of resistance \(R\), an ammeter, and a voltmeter, as shown in the circuit diagram. By adjusting the resistance \(R\), the student measures and records several pairs of the current \(I\) through the circuit and the corresponding terminal voltage \(\Delta V\) across the battery. If the student plots \(\Delta V\) on the vertical axis as a function of \(I\) on the horizontal axis, which of the following correctly indicates how \(\varepsilon\) and \(r\) are determined from the resulting best-fit line?