A particle of mass M may move with the velocity v, along AO, or DE or BC. Then which of the following statements is not correct about particle's angular momentum about point O.

When particle moves along BC or DE , its angular momentum will remain same about O, as its perpendicular distance remains same.

If the particle is moving along BC, $\overrightarrow{\mathrm{r}}\times \mathrm{m}\overrightarrow{\mathrm{v}}$ will be into the plane.

If the particle is moving along DE, $\overrightarrow{\mathrm{r}}\times \mathrm{m}\overrightarrow{\mathrm{v}}$will be out of the plane.

And since the magnitude of $\overrightarrow{\mathrm{r}}\times \mathrm{m}\overrightarrow{\mathrm{v}}$ and same in both cases the angular momentum will have same magnitude but are in opposite directions.