Eliminate B and D, not all single celled organism carry out through photosynthesis , they called singled celled organism and not work with other cell, it's either A and C, single celled organism is not a complex organism. so you can eliminate letter C.
so the best answer is A, although they have multiple organs system to maintain their internal stability.
the purpose of making a cloud inside the bottle is to make us understand how clouds are being formed
Your small intestine can absorb FRUCTOSE without any prior digested into smaller molecules. Fructose is usually find in fruits.
Glucose, fructose and galactose are the three monosacharides that are absorbed directly into the blood stream.