Lichens are not single organisms, but algae and fungi that function together. The algae use photosynthesis to make food for both organisms. The fungi produce digestive chemicals and absorb nutrients for both organisms. How does the biological activity of lichens cause weathering in rocks?
Answer options with 4 options
A.
Lichens cause friction as they grow, which weathers the rocks.
B.
Lichens produce chemicals, which dissolve and weather the rocks.
C.
Lichens take in water, which freezes in cracks and weathers the rocks.
D.
Lichens absorb heat during photosynthesis, which weathers the rocks.

The correct answer is B

Lichens produce chemicals which dissolve and weather rocks

the corpus luteum secretes estrogens and progesterone. the latter hormone causes changes in the uterus that make it more suitable for implantation of the fertilized ovum and the nourishment of the embryo. if the egg is not fertilized, the corpus luteum becomes inactive after 10–14 days, and menstruation occurs.

i hope this : )

hypoxemia refers to a below usual concentration of oxygen in the blood, mainly in the arteries. hypoxemia is an indication of an issue associated with circulation or breathing and may lead to various symptoms like shortness of breath.  

the condition is identified by determining the level of oxygen in the blood sample obtained from an artery. it can also be predicted by determining the oxygen saturation of the blood with the application of a pulse oximeter.  

the normal arterial oxygen is about 75 to 100 mm hg. the values underneath 60 mm hg is generally considered with the requirement for supplemental oxygen. the normal pulse oximeter readings generally range between 95 to 100 percent. the values under 90 percent are regarded as low.  

in the given case, the oxygen saturation is measured at 93 percent, hence, there is no need to administer oxygen, that is, one should withhold oxygen.