When Working with Life Tables, We Work with Many Variables

When working with life tables, we work with many variables and make many calculations. One such variable of importance is bx or fecundity. An important calculation we make as we determine the net reproductive rate is lxbx. This calculation is often referred to as "realized fecundity." Why might that be the case?

A) because we are looking at fecundity rate for females as well as considering how many females survive (survivorship rate) to each reproductive age class
B) because we are looking at both male and female survivorship at each age class
C) because we are looking at survivorship only at prereproductive age classes
D) because we are looking at survivorship only at postreproductive age classes