Correct option is C
A broad base means many young individuals (high birth rate), and a narrow top means fewer elderly (lower life expectancy but improving survival). This pattern indicates developing population with high birth rate and declining death rate.
Explanation of options: (a) ✘ High death rate would shrink base and midsection, not typical here. (b) ✘ Aging population has narrow base and broad top. (c) ✔ Correct; broad base = high fertility, narrow top = lower survival. (d) ✘ Low fertility populations show narrow bases.