Facts and observations that can be objectively observed and carefully measured using the five senses are known as . evidence.
b. key concepts.
c. correlatives.
d. spurious factors.

.a. evidence

Explanation:

Is a tangible support that proves that something is factual or true , as a result evidence since it works as a proof is must be something that one can see,touch ,hear ,smell and taste because it is meant to give a tangible proof of how truthful something is. Evidence are based on facts and observations.

the united states has a federal government. the president is the head of the federal government of the united states. however, each state forms its government for administration purposes. the powers of the state governments are exercised within restricted state boundaries. and citizens participate in this government by voting.

answer; pentagon papers, vietnam draft-resistor, james dean, american revolution;