GMAT Sentence Correction (SC) | Re: scientists theorize that tuberculosis

a. that lived at the same time as other legendary mammals -> not the time is compared to mammals, but the mammalslived at the same time as the legendary ones (lived)
B. that had lived at the same time as had other legendary mammals -> Why would you want to add past perfect here. According to your reasoning, the same mistake would still be present,
...

---