Q485234 - NUCEPE - 2016 - Prefeitura de Teresina - PI - Professor - Inglês

The pronoun this (in bold type in the 2nd paragraph) refers to

a) the fact that drugs that seem promising in lab and animal studies have a notoriously high failure rate in human trials.
b) phosphoethanolamine has been shown to kill tumor cells only in lab dishes and in mice, not humans.
c) some chemists at the University of São Paulo’s campus in São Carlos have manufactured the compound for years.
d) those patients who have claimed remarkable recoveries, perpetuating the compound’s reputation.
e) administrators at the university estimate that it covers about 80% of the orders they have received for the compound.