Final answer:
The size of the fungus as a function of time is best described by an exponential function (B). During the exponential growth phase, the population of organisms such as bacteria increases at an accelerating rate, which is exponential and not linear. A J-shaped growth curve represents this dynamic on a plot.
Step-by-step explanation:
The growth rate of a fungus or any organism can be described by different types of functions depending on the phase of growth and conditions. The logarithmic (log) growth phase, also known as the exponential growth phase, is characterized by organisms such as bacteria actively dividing and increasing in number exponentially. This means that during the log phase, the size of the population increases at a greater and greater rate as time progresses, which is typically represented by a J-shaped growth curve when plotted.
The fungus's growth described in the question is most accurately represented by an exponential function (B), especially during the phase where the conditions are ideal for active growth without nutrient or space limitations, and it can grow unrestrictedly. The relationship here is nonlinear and exponential—the rate of increase itself accelerates with time. If plotted on a semilogarithmic graph, this growth might appear linear, but in reality, it is exponential when viewed on an arithmetic scale.