Consider the following types of vehicles : 1. Full battery electric vehicles 2. Hydrogen fuel cell vehicles 3. Fuel cell-electric hybrid vehicles How many of the above are considered as alternative powertrain vehicles?

All three are correct because an alternative powertrain refers to any vehicle propulsion system—such as electric motors, hydrogen fuel cells, or their hybrids—that deviates from the traditional internal combustion engine (ICE) powered solely by fossil fuels. Option (b) is the most tempting wrong choice if one incorrectly assumes that hybrid systems are not "alternative" enough, but any integration of fuel cells or high-capacity batteries qualifies as an alternative technology. The core concept being tested is the classification of modern automotive technologies designed to reduce carbon emissions and dependence on petroleum.