Read the extract below.

Thiel’s “fight” involves investing millions in biotechnology and artificial intelligence in what he has called “the immortality project”. His investment firm Thiel Capital has, according to Inc, expressed an interest in a company called Ambrosia, which is running a trial where individuals can pay $8,000 to receive a blood transfusion from a teenager in the hope that it will restore some youthful vigour.

The highlighted relative pronoun “which” above refers to