This question seems to be incomplete. However, there is enough information to find the right answer.
Answer:
a. Steve Jobs cofounded Apple Computers with Steve Wozniak in 1976, but Jobs was phased out of the company during the 1980s after it experienced major setbacks.
Explanation:
The only one that uses punctuation marks correctly is option a.
The first comma in option b should be a period (making the first part a simple sentence) or a semicolon that links the two independent clauses.
The same happens with the first comma in options c and d, as it should be a period or a semicolon.
