Solution:

The answer is (D). Let $h$ be the number of working hours during the morning (and hence also during the afternoon). We know that Alberto prepares $2 h \cdot 90 = 180 h$ ravioli, while Barbara prepares $h \cdot 110 + h \cdot 70 = 180 h$ of them. Let now $t_1$ be the time Ciro takes to prepare the first $2 / 3$ of his ravioli, and $t_2$ the time he spends preparing the last third. If we call $r$ the total number of ravioli prepared by Ciro we then have
$$\left\{ \begin{array}{l} t_1 + t_2 = 2 h \\ t_1 \cdot 140 = \frac{2 r}{3} \\ t_2 \cdot 50 = \frac{r}{3} \end{array} \right.$$
We can then write $t_1 = \frac{2 r}{3 \cdot 140}$, $t_2 = \frac{r}{3 \cdot 50}$, and substituting into the first equation we find $r \left( \frac{1}{210} + \frac{1}{150} \right) = 2 h$, from which $r = 175 h$.