a)

$2^3=8$

$2\cdot 3=6$

$2^3>2\cdot 3$

b) 

$4^2=16$

$4\cdot 2=8$

$4^2>4\cdot 2$

c)

$1^4=1$

$1\cdot 4=4$

$1^4<1\cdot 4$