When you are using the word "advice", you are most of the time talking about some advice that you have already given or are going to give. You would use the word like "that's my advice" or "ill give you my advice", or even "I'm just giving you advice". The word advise can be used for many different scenarios. In this case, it is right because it is saying "I would strongly _____", and if you put in the words, you can hear if they sound right or not. I would strongly advice does not work because you are receiving advice, but the sentence is not talking about the advice it is giving, it is just trying to advise you. When using the word advise, it is mainly going to be used when somebody is trying to help you with something. Like right now, I'm advising you about this vocabulary. So I'm going to advise you on what the correct choice is. You could also so I'm giving you my advice. So I'm going to give you my advice on what you should pick. I hope you can see the difference in context in each sentence when using each word.
This is a hard one and I can see why you decided to post it here. B is most definitely wrong but the other three are all neck and neck. There are both even pros and cons of A and C but I think it would be more reasonable to adopt a general routine. So I think the answer would be C.
