Answer:
b. a canker on a plant stem
Explanation:
A canker on a plant stem -
It is the clear and strong evidence of a plant suffering from a disease which is due to pathogens.
According to the question , other options , stunted growth and soft rot, are not caused because of pathogens , they are due to genetic reasons .
And, the option, mycelium of a pathogen , is not a plant disease .
Hence , incorrect option .
Therefore , from the options , the correct one is - a canker on a plant stem .
Answer:
Economists study the ways a society uses scarce resources such as land, labor, raw materials, and machinery to produce goods and services. They analyze the costs and benefits of distributing and consuming these goods and services.