The relationship of species richness and area is a straight line as per the equation.However , on logarithmic scale it can be defined as
logS = logC + logZ
logS = logZ + logA
logS = logc + ZlogA
logS = logA + ClogA
As learnt in Patterns of Biodiversity - Species-Area relationships -
On a logarithmic scale, the relationship is a straight line described by the equation:
log S = log C + Z log A
where,
Hence, the correct option is (c).