When a yellow coating is paired with thicker coating, this indicates Dampness and Heat together. Damp-Heat. This is the ONLY sign that is showing that there might be some Heat present. Whenever you have one sign or symptom that is odd, put it aside and create a diagnosis with the ones that create a group and make the most sense. In this case, there is more tendency for the coating to be sticky and slimy. This means a lot of Dampness which adds up with the other signs and symptoms.
Also, I’d like to mention that this question is just hard to begin with because it asks for the ‘most accurate’ diagnosis – and then lists four. In my opinion, the correct diagnosis would be Spleen-Yang Deficiency. However, it’s not there, so we have to pick Spleen-Qi Deficiency.
In summary: if you have 2 or more signs and symptoms that are leading you to a TCM diagnosis, this is a good thing. If you have one odd symptom, put it aside to see if it makes sense (or not!) after you’ve come to your conclusion.