9. Which of the following forms of renewable energy uses the sun's energy most directly?
a. biomass fuel
b. passive solar heating
C. geothermal energy
d. a hydrogen fuel cell

b. passive solar heating

Explanation:

Passive solar heating is a system designed to use solar energy (energy from the sun) for the purpose of providing electricity or heat. This system is used in households and offices to absorb, retain and supply heat to the desired location.

This system is termed "passive" because it does not require any external device for conversion of solar energy rather it exploits sun's energy directly. Hence, according to this question, PASSIVE SOLAR HEATING is the form of renewable energy that uses the sun's energy most directly.

B. passive solar heating

Explanation:

Photovoltaic (PV) systems use solar cells to convert sunlight into electricity. Solar hot water systems can be used to heat buildings by circulating water through flat-plate solar collectors.

explanation:

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.