Christian Aid – fine
Cafod - fine
Traidcraft - fine This gets five star rating from me because you can easily talk about their work.
Caritas - fine
Tearfund - fine
Oxfam - No because it is not a Christian aid agency.

You then have to know how the agency puts Christian beliefs into practice.

Know Christian beliefs
Old Testament beliefs about attitude to the poor.
New Testament Jesus’ statements about the poor.
Jesus’ attitude towards outcasts.

What you are asked to write about though is
How these are put into practice ie what sort of work do they do that ties in with Christian principles.