"I do not see a thing."
Translation:Ich sehe nichts.
If "Ich sehe nichts" is the preferred answer, then surely the question ought to be "I see nothing" ?
Right: I wrote 'ich sehe gar nichts' (wrong, btw) as I thought that, too. I don't see a thing seems stronger than I see nothing.
"Ich sehe nicht" would be translated as "I don't see". "Ich sehe nichts" means "I see nothing".
To my understanding, when we want to negate nouns we use kein instead of nicht. Otherwise it sounds strange. Please correct me if I am wrong.
I haven't tried it but, "Ich sehe keine Sache," should be accepted.
"keine" serves as the indefinite article. Also, being that Sache is fem, it would be eine, e.g., Ich sehe eine Sasche (I see a thing).