Answer:
Ambani the most enterprising Indian entrepreneur, was born on December 28 1932. Ambani started his entrepreneur career by selling Bhajas.
The correcting verbs in the sentence should be their past tenses of the verbs in brackets as the text is relating to events in the past.
The past tense of be is was and the past tense of start is started and when the past tense verbs are put into the sentence it would read correctly as the shown above.