"what do you think our candidate should do to increase her credibility with voters? " is an example of which type of question

The answer is "open question".

Open questions are questions which can't be replied with just 'yes' or 'no'. A considerable lot of them start with 'what': why, where, who and so on. Open inquiries can be contrasted with shut inquiries, which require just yes or no answers.  

Utilizing open questions can be frightening, as they appear to hand the stick of control over to the next individual. Be that as it may, very much set inquiries do abandon you in charge as you steer their advantage and connect with them where you need them.

add the answer choices and i'll give you the answer

for your question the answer would have to be france