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: Hydrogen vehicles
 Argument: Hydrogen is non-toxic, unlike most fossil fuels.
in favor

Topic: Banning vuvuzela horns at the 2010 World Cup
 Argument: Vuvuzela sales are economically beneficial in S. Africa.
against

Topic: Gay adoption
 Argument: Children raised by same-sex parents are not more likely to have same-sex orientations themselves.

in favor