Which statement describes two organ systems working together to deliver nutrients to cells?
A. The blood absorbs the nutrients that the digestive system obtains
from food.
B. The molecules of important nutrients are made from food in the
digestive system.
C. The respiratory system transfers oxygen removed from nutrients
to the blood.
D. The excretory system removes excess nutrients from blood as it
makes urine.

the three components of a nucleotide are the nitrogenous base, the phosphate group and the five-carbon sugar.

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.

the answer is lactic acid from anaerobic respiration. the acid in lactic acid is what creates sore and burning muscles. if you think about how acid burns that will give you a clue for questions like this.