When a country is ravaged by a pandemic of the magnitude that AIDS is in SubSahran Africa, what happens to the shape of its population pyramid?

a$.$ the bottom of the pyramid shrinks $($fewer numbers of infants$)$

b$.$ the top of the pyramid becomes very wide $($large number of old people$)$

c$.$ the middle of the pyramid shrinks dramatically $($working age population decimated$)$

d$.$ nothing happens to the pyramid$-$AIDS does not kill enough people to affect the overall population