I figure these out using a Venn diagram. I'd draw three interlocking circles and name one "manners," one "morals," and one "social in nature."
I'd shade out every part of the manners circle that does not overlap with the social in nature circle, as manners are necessarily social in nature. I would not cross out any part of the morals circle, as they are not necessarily social in nature, indicating that they may or may not always be social in nature.
What this means is that the only place that manners overlaps with morals is when both of them also overlap with social in nature.
This type of diagram helped me the most, particularly with the questions meant to trick, such as, "The information above suggests that all manners that are social in nature are also morals." That seems reasonable, but if you look at the Venn diagram, you'll see that there is a section of the manners bubble that overlaps with the social in nature circle but not the morals circle.