Which one of the following graphs represents the velocity-time $(v-t)$ graph of a small spherical body falling in a viscous liquid?

Two spherical soap bubbles of radii $r_1$ and $r_2$ in vaccum coalesce under isothermal condition．The newly formed bubble has a radius（ $r$ ）given by

A pipe $A$ is connected with other pipes $B$ and $C$ as shown in the figure．The areas of cross－section of $A, B$ and $C$ are respectively $\alpha, \frac{\alpha}{2}$ and $\frac{\alpha}{4}$ ．If the velocities of flow of water through $A$ and $B$ are $10 \mathrm{~m} / \mathrm{sec}$ and $6 \mathrm{~m} / \mathrm{sec}$ ，respectively，then velocity of flow，$V_c$ along $C$ is

Two wires A and B of same length are made of same material. Load (F) vs. elongation (x) graph for these two wires is shown in the figure. Then which of the following statement(s) is/are true?