Read the sentence below, which appears in the brochure “Nanotechnology: Big Things from a Tiny World.” As you read, look for context clues that could help you define any scientific terms. Scientists have also developed sensors to measure pesticide levels in the field, allowing farmers to use less while still protecting their plants.

According to the context clues provided by the author, what is a pesticide?

a. something that develops sensors
b. something that protects plants
c. something that farmers develop
d. something that monitors pests