"Я не люблю красный."
Translation:I do not like red.
With the masculine adjective, I thought that red describes some noun. That's why I answered "...the red one."
I thought the same -- it's an adjective, thus implying a noun, rather than meaning "I don't like (the colour) red"
If you wrote, "I don't like red," and it marked you incorrect, then report it.
probably because the word for color is masculine: Красный цвет. This exercise seems to be talking about the color itself. However if you use the feminine or neuter, Я не люблю красную/красное, then you are most likely referring to some feminine or neuter noun that happens to be red. For example,
-Я люблю эти машины. -Я не люблю красную.
-"I like these cars." -"I don't like the red one."