HMHS Britannic (/ brtnk /) was the final vessel built of the White Star Line's Olympic class of steamships, she was the fleet mate of both the RMS Olympic and the RMS Titanic and was intended to eventually enter service as the transatlantic passenger liner.

Answer this question based on the passage: what was the name of the titanics sister ship? Okie... think carefully first, then make a decision:
This is the relevant information: HMHS Britannic (/ brtnk /) was the final vessel built of the White Star Line's Olympic class of steamships, she was the fleet mate of both the RMS Olympic and the RMS Titanic and was intended to eventually enter service as the transatlantic passenger liner. So, the answer is HMHS Britannic.