Why is the constitution considered a living document?
a. it allows for checks and balances
b. the president has the ability to veto changes
c. amendments can be added to change it
d. courts can provide judicial review

D. Courts can provide judicial review

Explanation:

Living Constitution is considered in frames of a theory that has developed in American constitutionalism, which claims that the content of the constitution is dynamic and develops under the influence of social changes. The idea of a “living constitution” is that the current state of society should be taken into account when interpreting key constitutional phrases created in the 18th century.

To date, the really functioning (“living”) US Constitution is a synthesis of the constitutional text with a series of judicial precedents built in the form of constitutional doctrines that give the Basic Law (which is difficult to formal changes) the flexibility and dynamism necessary for social maneuvers in a changing reality.

Under the "living" constitution, the following should understood: acts of interpretation of the Constitution by the US Supreme Court; states’ constitutional norms; judicial precedents; laws (bills) of Congress; acts of the President.

the answer to your question is a. the salt plains

in 1811, he led an expedition, known as the george c. sibley expedition, to improve relations with the pawnee and kansa tribes, and also to locate the rumored jefferson's salt mountain

i think the answer is b.