A small sphere is suspended by a string of length l. The sphere is making oscillatory motion between extreme positions A and B then 

Solution:

At the extreme positions A and B, velocity is zero. Tension induced in the string is always perpendicular to the direction of motion. Since power delivered by tension is $\overrightarrow{\mathrm{T}}.\overrightarrow{\mathrm{V}}$, it is always zero. 

Power delivered by gravitational force is ${\overrightarrow{\mathrm{F}}}_{\mathrm{g}}.\overrightarrow{\mathrm{V}}$. At position C, $\overrightarrow{{\mathrm{F}}_{\mathrm{g}}}$ and $\overrightarrow{\mathrm{V}}$ are mutually perpendicular and at the extreme positions $\overrightarrow{\mathrm{V}}$ is zero. So option (1) is also right. Therefore, (4) is the correct option.