The option VariableName => q changes the symbol used for intedeterminates in a polynomial ring created with markovRing.
The object VariableName is a symbol.
The source of this document is in /build/macaulay2-88fgJW/macaulay2-1.25.11+ds/M2/Macaulay2/packages/GraphicalModels.m2:1888:0.