Stuff like grass and trees. anything that makes its own energy is a producer.
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.
T would be 31.5% - the same as A. C and G would be about 18.5% each. A & T and C& G are always found in about the same percentages of each other. A = T (Total of 63%, subtract from 100 = 37% which will be equally shared by G and C at 18.5)
