To determine which battery rating is tested at [tex]\( 0^{\circ} F \left(-18^{\circ} C \right) \)[/tex], we need to understand the different battery ratings provided in the choices:
1. Cranking amperes (CA): This is a measure of the current a battery can deliver at [tex]\(32^{\circ} F \left(0^{\circ} C \right) \)[/tex] for 30 seconds and maintain at least 1.2 volts per cell.
2. Battery voltage test: This typically refers to measuring the battery's voltage to determine its state of charge or health. This type of test doesn't have a specific temperature association.
3. Reserve capacity: This rating represents the number of minutes a fully charged battery at [tex]\(80^{\circ} F (27^{\circ} C) \)[/tex] can be discharged at 25 amps before the voltage drops below 10.5 volts.
4. Cold-cranking amperes (CCA): This measures the current a battery can deliver at [tex]\(0^{\circ} F \left(-18^{\circ} C \right) \)[/tex] for 30 seconds and maintain at least 1.2 volts per cell.
Given these definitions, the rating that is tested specifically at [tex]\(0^{\circ} F \left(-18^{\circ} C \right) \)[/tex] is:
D. Cold-cranking amperes (CCA).