Neutron activation analysis involves bombarding specimens with neutrons and then measuring the resultant:
a. x rays.
b. gamma rays.
c. beta particles.
d. alpha particles.

b. Gamma rays.

Explanation:

Neutron activation analysis is used for non-destructive analyses on substances like solids, liquids, gases e.t.c. involving little or no preparation.

Neutron activation analysis involves bombarding specimens with neutrons gives resultant gamma rays.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.