Lo que + superlative

Question

One question on a quiz I just took was something like

_________ menos me impresiona del cuadro es el color. (What impresses me least about this picture is the color.)

I entered 'Lo que el,' which was wrong. The correct response was 'Lo que.' To me, this seems to mean 'What impresses me less..., ' and it strikes me as a tricky combination of the lessons about 'lo que, etc', and 'el menos/la menos etc.' The lesson that I was referred to for review was the 'lo que etc.' lesson, but I found no example of it used immediately followed by a superlative.

It's been my understanding that an article is required to form a superlative (as in - menos=less, el/la/los/las/lo menos=the least). So it seems that the superlative article gets dropped immediately after 'lo que?' What if the sentence had been constructed slightly differently, 'Lo que me impresiona el menos del cuadro es el color?'

Accepted Answer

Hola E
When making this superlative "the most/the least" with "lo que" as in "what + verb + the most/the least (e.g. what I like the most, what suprised me the least..) we don't add the article to más or menos as these are adverbs. The translation in English makes you think you need an article, but not in Spanish.
I looked at the lesson for "lo que" and you're right by saying we don't have any example in it showing this structure with the superlative so we will either add it to that lesson or create a new lesson for this specific structure. 
I hope it helps.
Saludos cordiales.
Inma

Answer

Lo que menos me impresiona means - The thing that or what least impresses me. We cannot use a definite article with lo que because they are not talking about a concrete thing or as the lesson says it's something neutral or an abstract idea.