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

$1.$ Assets within a $403($b$)$ plan may be invested in individual securities$.$

$2.$ A $403($b$)$ plan usually provides a $3-$ to $7-$ year graduated vesting schedule.

$3.$ A $403($b$)$ plan must pass the ACP test if it is an ERISA plan.

$4.$ 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.