[SYMM]

I'd be tempted to treat it more like a graph then just an array of answers, something like:

Survey survey = new Survey();
SurveyQuestion q1 = new SurveyQuestion('Do you feel sick?');
SurveyQuestion q2 = new SurveyQuestion('Have you been physically sick?');
SurveyQuestion q3 = new SurveyQuestion('Do you have a headache?');

q1.setSuccessor('yes',q2);
q1.setSuccessor('no',q3);
q2.setSucessor('no',q3);
// etc.
q2.setSuccessor('yes',new EndPoint('You have food poisoning'));

survey.setup(q1,q2,q3);

while(!survey.hasEnded()) {
  survey.presentNextQuestion();
}
survey.showResult();

in java-esque pseudo-code.

Replacing the hard-coded survey setup with something database- or file-driven would be fairly trivial.