Which of the following provides the best estimate of world’s biological diversity?

Of about ten million species probably alive today, some 20 species are lost everyday, most of them unknown because no more than half a million have been actually identified.

Of about thirty million living species, some 50 are lost everyday, most of them unknown because no more than one million have been actually identified.

Of about forty five million living species, some 100 are lost everyday, most of them unknown because no more than 1.5 million have been actually identified.

Of about seventy five million living species, some 500 are lost everyday, most of them unknown because no more than 3 million have been actually identified.