The human population growth graph is:

"In the absence of environmental resistance, the population grows in a geometrical ratio when the food is given in an arithmetical ratio." This is:

In a population,the number of pre-reproductive age organisms is more than the post-reproductive age organisms. As a result,the population will .....

If the population at time $t$ is $N_t$,then its population at time $t + 1$ is . . . . . . .

Read the following statements and determine how many of them are correct:
$(1)$ Population is the total number of individuals of a species in a given area at a given time.
$(2)$ Developed countries show a low birth rate.
$(3)$ An equal proportion of reproductive and post-reproductive age individuals indicates a stable population.
$(4)$ In the presence of limited resources,the growth curve is sigmoid ($S$-shaped).

In a population,unrestricted reproductive capacity is called