Question

(22) The mummy was nicknamed Ötzi the Iceman. (23) This is because he was found preserved in the snow.

What is the best way to combine sentences 22 and 23?

The mummy was nicknamed Ötzi the Iceman because he was found preserved in the snow.
Despite being found preserved in the snow, the mummy was nicknamed Ötzi the Iceman.
This is because he was found preserved in the snow, but the mummy was nicknamed Ötzi the Iceman.
The mummy was nicknamed Ötzi the Iceman although this is because he was found preserved in the snow.