Answer
$(B)$
Work Step by Step
Goal: $\displaystyle \quad f(x)=\frac{N}{1+Ab^{-x}}$,
where $N$ = limiting value = $1300-1350$ (A and C are eliminated)
Cases B and D both have A=$4.2$, so we don't observe $f(0)$.
The graph is rising, so $b\gt 1, $ eliminating D.
