A very controlled research design to test relationships between variables is a:

A very controlled research design to test relationships between variables is a:

a) Survey
b) Field Experiment
c) Field Study
d) Lab Experiment

I say d).......

Because the experimenter determines the experimental conditions. It is therefore 'Manipulated' by the researcher. It would be conducted in a Lab environmnent, hence being classed as a 'very controlled' research design.

a) is 'how' initial data is collected on the variables,
and anything 'field' is usually observational with no control of the experimenter, and it would be very hard to conduct a very controlled manipulated experiment(b), somewhere out in the Savannah!

cheers :-)