SCHOLAR:IGNORANT::

Scholar (adj) means a person who has a lot of knowledge about a particular field(s) whereas, ignorant (adj) means someone who lacks knowledge, which means both of these are opposites.

In the options above, hardworking (someone who works a lot) and lazy (someone who is reluctant to work) - this is the only opposite pair, so the right answer is Hardworking: Lazy because,
Knife and sword are objects that are used for similar purpose (cutting, slicing);
Courage, bold indicate similar meaning - the action of doing something despite knowing the risks;
Luxury and wealth may go hand in hand as wealthy people (someone who possesses abundance of financial resources/possessions) can afford luxury items(something expensive but not a necessity), so there is some similarity in luxury and wealth.
However, for hardworking and lazy there is no similarity.