Detailed Explanation:

Maurya dynasty ruled from 322 BCE to 185 BCE, founded by Chandragupta Maurya.

Shunga dynasty ruled from 185 BCE to 73 BCE, established by Pushyamitra Shunga after the last Mauryan ruler.

Kanva dynasty ruled from 73 BCE to 28 BCE, replaced the Shungas.

Kushana dynasty ruled from 1st century CE to 3rd century CE, much later period.

Correct chronological order: Maurya (2) → Shunga (1) → Kanva (4) → Kushana (3), i.e., 2-1-4-3.