- Number theory is rich in problems of an especially (i)------- sort: they are tantalizingly simple to state but (ii) ------- difficult to solve.
A cryptic… deceptively
B spurious… equally
C abstruse… ostensibly
D elegant… rarely
E vexing …notoriously
The answer is E.
I can’t use math strategy for these blanks to get ‘vexing’. could you please help me?