What will come at the place of question mark ? 2/3 , 4/7 , ? , 11/21 , 16/31

The answer is $\boxed{\frac{7}{13}}$.

The sequence is $\frac{2}{3}, \frac{4}{7}, \frac{7}{13}, \frac{11}{21}, \frac{16}{31}$. The common ratio is $\frac{7}{12}$. This means that each term is $\frac{7}{12}$ times the previous term.

To find the missing term, we can multiply the first term by $\frac{7}{12}$. This gives us $\frac{2 \times 7}{3 \times 12} = \frac{7}{13}$.

Therefore, the missing term is $\boxed{\frac{7}{13}}$.

Here is a brief explanation of each option:

• Option A: $\frac{5}{9}$ is not in the sequence.
• Option B: $\frac{6}{11}$ is not in the sequence.
• Option C: $\frac{7}{13}$ is in the sequence.
• Option D: $\frac{9}{17}$ is not in the sequence.