Which of the following statement$($s$)$ regarding $403($b$)$ plans is true?

Assets within a $403($b$)$ plan may be invested in individual securities$.$

A $403($b$)$ plan usually provides a $3-$ to $7-$year graduated vesting schedule.

A $403($b$)$ plan must pass the ACP test if it is an ERISA plan.

In certain situations, a participant of a $403($b$)$ plan can defer an additional $$15,000$ as a catch$-$up to the $403($b$)$ plan.