Which of the following is one observation that darwin made as he developed his theory of natural selection?
a. fish, such as salmon, lay few eggs but produce many offspring.
b. fish, such as salmon, never produce offspring.
c. all organisms that are born survive.
d. more organisms are born than can survive.

The correct answer is D. More organism are born than can survive

Explanation:

Darwin's Natural Selection Theory explains evolution takes place as there are differences between individuals that make only some of them survive as changes in environmental conditions make certain traits to prevail over others. This theory was created based on Darwin's observations in different ecosystems in which he found there were slight differences between organisms of the same species and also that more organisms are born than can survive, due to this observation Darwin found only those that are best adapted will survive and reproduce which explains natural selection. Thus, the observation Darwin made as he developed his theory of Natural Selection was "more organism are born than can survive".

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.

oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%