In conservation plowing, why are dead weeds and stalks of the previous year's crop left in the ground? a. to keep the soil from becoming too fertile
b. to reduce the amount of seed needed for the next year's crop
C. to retain moisture and hold the soil in place
d. to keep more organisms out of the soil

to retain moisture and hold the soil in place.

Explanation:

this technology of putting dead plants on the soil under the plants and the area nearing the plants is called mulching.it is helpful in reducing the rate of evaporation and also reduces soil erosion.

the reason the two sea urchins don't compete with each other for food, resources, etc. is because the urchins have adapted to the environment but they have also adapted to each other. this is most likely because the genes of the sea urchins.

one part of the electromagnetic spectrum that arrives on earth as solar radiation from the sun is the visible spectrum. wavelengths of the visible spectrum combine to form what we refer to as

answer - d) ultraviolet radiation.

violet /   380–450 nm / 668–789 thz

violet is number 1 in the chart of visible light.