Scientists believe were the first types of cells able to make their own food.
a. cyanobacteria
b. chemoautotrophs
c. photoautotrophs

a. cyanobacteria

Explanation:

Cynobacteria is considered to be the first organism on earth which was capable of producing it's own food by the process of photosynthesis. The cynobacterial strain used to exists on earth around 3.5 billion years ago. These were the first unicellular prokaryotic organisms. They had a large number of colonies. These were responsible for the liberation of large amount of oxygen in the oxygen deficient primitive earth atmosphere.    

relative humidity, temperature and dew point -- are bound together in the mathematical relationship below. relative humidity changes when temperatures change. because warm air can hold more water vapor than cool air, relative humidity falls when the temperature rises if no moisture is added to the air. so i would say a

answer:

the water molecules are transferred from the roots to the stem or top parts of the tall tree because of important properties of water which are adhesion, cohesion and capillary action. cohesion is the property of water molecules keeps water molecules in a combined state by sharing of bonds between them at the atomic level. adhesion allows the interaction of water molecules with other substances or substrate. adhesion will cause the attachment of water molecules to the wall of the vessel (xylem) of the plant. capillary action occurs when the adhesive force to the vessel wall is stronger than the cohesive force between water molecules. capillary action mimics the transfer of water from a tube or pipe. in this way water utilizes its property to transfer water from down to top level of the plant.