Which of the following is a consequence of biological magnification (biomagnification)?
a. toxic chemicals in the environment pose greater risk to top-level predators than to primary consumers.
b. the amount of biomass in the producer level of an ecosystem decreases if the producer turnover time increases.
c. populations of top-level predators are generally smaller than populations of primary consumers.
d. only a small portion of the energy captured by producers is transferred to consumers.

Option (a).

Explanation:

Biological magnification may be defined as  the increase in the concentration of the harmful chemicals at the top levels in the food chain. The chemical or substance may not get degraded and accumulate in the higher tropic levels.

These toxic chemicals pose greater problem to the environment.  The toxic substance pose greater problem to the top level predators than the primary consumers because top predator directly feed on the primary consumers. The toxic chemicals get accumulate in their tissue.

Thus, the correct answer is option (a).