Who was the first batman on out 99 run in cricket?

The first batsman to score a century in One Day Internationals (ODIs) was East Africa's Zafar Ansari, who achieved this milestone on February 24, 1975, against England during the inaugural ODI match. However, if you meant "batting" in terms of the ODI format, the first player to bat in ODIs was also Zafar Ansari, as he opened the innings in that match.