Define Anomers?

Question

$\begin{array}{1 1} \text{(a) Anomers are stereoisomers of cyclic sugars that differ in configuration only at the hemiacetal or hemiketal carbon.} \\ \text{(b)Anomers are stereoisomers of acyclic sugars that differ in configuration only at the hemiacetal or hemiketal carbon.} \\ \text{(c)Anomers are diastereomers of cyclic glucose that differ in configuration only at the hemiacetal or hemiketal carbon.} \\ \text{(d) Anomers are diastereomers of cyclic sugars that differ in configuration.}\end{array}$