The total weight of all the ants in the world is much greater than _________ .
to all human beings
all human beings are that
that of all human beings
is of all human beings
Explanation: In the comparative sentence, two objects must be put in the same form, in the former clause we used “total weight of”, then in the latter part we need to use “that of”.
The total weight of ants in the world is much more than the weight of humans.