Scientists search for fossil fuels in many ways. Which type of surveying involves sending a sound wave into the ground (by exploding dynamite, thumping the ground with a large weight, or using an electric vibrating machine) and measuring its return to the surface at receiving stations is called surveying.

A. dynamite
B. destructive
C. seismic
D. sonar
E. geologic

Afarmer who is grown corn for the past five years notices in the sixth year that the his harvest is significantly smaller, despite an increase in labor on the farm. the following year, the harvest continue to decline. which of the following explanations most plausibly accounts for the reduction in corn yield? a) soil degradation b) desalinization c) better irrigationd) terracing