What evidence tells scientsts that Earth's core is solid?

Explanation:

A PKJKP traverses the inner core as a shear wave, so this is the direct evidence that the inner core is solid," Cao told LiveScience, "because only in the solid material the shear wave can exist. In the liquid material, say water, only the compressional wave can travel through."

answer; (b); i believe its indefinite existence of human population in a healthy and prosperous condition;

primary groups shape your individual development

explanation: