The La Brea Tar Pits in Los Angeles are the site of millions of fossils from the ice age. Woolly mammoths, giant sloths, dragonflies, and other plants and animals from this era have been found in these pits. Scientists at the tar pits discovered that many of the smaller animals they extracted from the pits still exist around Los Angeles today. But many of the larger mammals—such as woolly mammoths and saber-toothed tigers—are now extinct. Why do you think this is the case? What can scientists learn about Los Angeles’ climate history by studying the specimens found in these tar pits?

option a is correct i.e.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.

the answer to you question is   jet streams

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.