Darwin’s hypothesis about evolution is considered a “theory.” What does this mean? Is it just a guess?

What is the term for the two sets of chromatids formed in the parent cell a.haploid b.diploid c.gamete d.tetrad

Ascience research group is testing a new type of plant food. one trial is conducted in a controlled experiment. the data from the trial show that the plant that received the new food grew faster than the control plant. the group announces that the new plant food makes plants grow faster. what is the main weakness in this scientific claim?

Eutrophication caused by human nutrient pollution.