[w451208]

[majorjp]

Essentially yes, this is a reaction with a Grignard reagent and a terminal alkyne. In this case the sp hybridization of the C-C triple bond makes the teminal hydrogen quite acidic therefore the acidic hydrogen would attack the Gringnard reagents nucleophilic R-group to form ethane, leaving a negative charge on the alkyne and a postive charge on the Mg-Br complex.

[w451208]

Thanks for your help. Could you help me with this one as well. Why cant the answer be B?

[orgopete]

I see you are having a problem understanding the curved arrow convention. Try printing out and doing the problems here:
http://www.curvedarrowpress.com/agocm/inside/sampler/sampler.html

[karlosshughes]

Thanks for your help. Could you help me with this one as well. Why cant the answer be B?

Because amines are not electrophilic. Enolates are nucleophilic on carbon and these will react with electrophilic species, such as carbonyl compounds but not amines. The nitrogen already has a full octet and so can't accept any more electrons, which is what would happen if the double bond attacked the nitrogen.