Determine the intervals for which the function is concave up or concave down. State the inflection points.
$f(x)=\frac{7}{2x-9}$

• A. Concave down: $\left(-\infty,\infty\right)$; No Inflection Points
• B. Concave up: $\left(-\infty,\infty\right)$; No Inflection Points
• C. Concave down: $\left(-\infty,\frac92\right)$ ; Concave up: $\left(\frac92,\infty\right)$; Inflection point: $\left(\frac92,0\right)$
• D. Concave down: $\left(-\infty,\frac92\right)$ ; Concave up: $\left(\frac92,\infty\right)$; No Inflection Points

Answer: (D)