The correct answer is Option 1 - 1-2-3-4
Chronology of given events:
1- Origin of Mahajanpadas - 600-500 BCE:
2- Invasion by Alexander - 327-325 BCE
3- Reign of Ashoka - 272/268-231 BCE
4- Accession of Kanishka - 78 CE: Accession of Kanishka took place
Timeline of Ancient Indian History:
600-500 BCE: Establishment of Mahajanapadas
500- 400 BCE: Rulers of Magadha consolidate power in northern India
327-325 BCE: Invasion of Alexander of Macedonia.
272/268-231 BCE: Reign of Asoka.
200-100 BCE: Indo-Greek rule in the northwest; Cholas, Cheras and Pandyas in south India; Satavahanas in the Deccan
100 BCE-200 CE: Shaka (peoples from Central Asia) ruled in the northwest
78 CE: Accession of Kanishka took place (Kushanas).
320 CE: Beginning of Gupta rule
335-375 CE: Samudragupta
375-415 CE: Vakatakas rule in the Deccan
606-647 CE: Harshavardhana king of Kanauj (The Pushyabhuti dynasty, also known as the Vardhana dynasty ruled in northern India during the 6th and 7th centuries.) | 
