Unfortunately, many students of mathematics are unaware of the contributions of Srinivasa Rmanujan, a genius who in his short career produced a number of theories that are breathtaking in both their profundity and beauty.
1. are unaware of the contributions of Srinivasa Rmanujan, a genius who in his short career produced a number of theories that are breathtaking
2.are unaware of the contributions of Srinivasa Rmanujan, a genius who in his short career produced a number of theories that had been breathtaking
3. are unaware of the contributions of Srinivasa Rmanujan, a genius who in his short career had produced a number of theories that are breathtaking
4. are unaware of the contributions of Srinivasa Rmanujan, a genius who in his short career produced a number of theories that is breathtaking
5. had been unaware of the contributions of Srinivasa Rmanujan, a genius who in his short career had produced a number of theories that is breathtaking
#2 - had been is wrong
#3 - had produced is un-necessary
#4 - "the number of" is singular, "a number of" is plural. This is wrong since this uses the singular "is"
#5 - had been is absurd
so, #1 is correct