It would be d because a cell is least complex and organ system is most complex
All living creatures are classified into systems and sub-systems based on their similar characteristics. They are divided from bigger groups into smaller groups based on the detail of their similarities i.e. how they look, move, reproduce and how they relate to each other. A practical way of understanding the classification of living organisms is that organisms are linked to other similar organisms via family trees. The classification of all living creatures includes at least four levels: order, families, genus and species.
Carbonate groups contain a single carbon atom, and three oxygen atoms in a trigonal molecular geometry. The carbon atom has two single bonds to two oxygen atoms and a double bond to the third oxygen atom. Therefore, in addition to carbon, carbonate minerals contain oxygen. An example of a carbonate mineral is calcium carbonate, often found within rocks.
Go to google.................
Evolution Due to environmental factors, It may not look it, but, needles are leaves, they collect solar radiation to produce glucose through the process of photosynthesis, however, needles are, some would say, evolutionary superior to leaves. Needles themselves hold in more water due to their dense wax coating, they are very difficult for insects and other organisms to eat, one because of their structure, and two because of their acidity, they can catch sunlight all year long due to their winter resilience( they don't fall, during the winter), and they have less surface area for wind to catch, which leaves them better protected from wind than most deciduous trees, however the surface area can also pose a larger problem for less surface area means less sunlight interception, therefore more are needed to compete against regular leaves. But.. I Digress... Plant needles are 'PROBABLY' initially the result of evolution of narrow leaves due to climate or environmental factors.
Sry its so long got carried away! Hope this helps xD
