A student investigates the ionising radiation emitted by a radioisotope by measuring the corrected count rate at various distances in air using a Geiger-Müller (GM) tube. The results are shown in the graph below:

Which of the following correctly identifies the radiation type emitted by the source and its approximate maximum range in air under these conditions?
Radiation type: β−\beta^-β−, Approximate maximum range: 4 mm4\text{ mm}4 mm
Radiation type: α\alphaα, Approximate maximum range: 4 cm4\text{ cm}4 cm
Radiation type: β−\beta^-β−, Approximate maximum range: 4 m4\text{ m}4 m
Radiation type: α\alphaα, Approximate maximum range: 4 mm4\text{ mm}4 mm