Given the Target and Argument texts detect the stance that the argument has towards the topic. There are three types of stances "in favor", "against", and "neutral". 

Topic: Natural gas vehicles
 Argument: Odorless natural gas can escape detection risking fire/explosion.
against

Topic: Abolition of nuclear weapons
 Argument: It's not possible to abolish nuclear weapons now that the are at large.
against

Topic: Mandatory labeling of genetically modified foods
 Argument: Insects are likely to become resistant to GM crops.

against