Write Interval Notation for the Given Set or Graph $a+9<21$ A) $\{\mathrm{a} \mid \mathrm{a} \geq 12\}$

Write interval notation for the given set or graph.
- $a+9<21$

A) $\{\mathrm{a} \mid \mathrm{a} \geq 12\}$ , or $[12, \infty)$

B) $\{\mathrm{a} \mid \mathrm{a}<12\}$ , or $(-\infty, 12)$

C) $\{\mathrm{a} \mid \mathrm{a} \leq 12\}$ , or $(-\infty, 12]$

D) $\{\mathrm{a} \mid \mathrm{a}>12\}$ , or $(12, \infty)$