$*2543*=2\times3+5\times4=6+20=26$.  So the answer is $\rm C$. 
If $*abcd*=a\times d+b\times c$, then $*2543*=$~\uline{~~~~~~~~~~}~. ($2004$ Math League.com contest problem, $8$\textsuperscript{th} Grade, Question \#$33$) 
(A) $$14$$ 
(B) $$22$$ 
(C) $$26$$ 
(D) $$120$$ 