The correct answer would be the second option. The correct plan for his experiment would be that the temperature, the type of limestone, and the type of acid are controls. The amount of acid and the amount of damage to the limestone are variables. To determine the degree of damage of the acid it would be best that the amount of acid is the manipulated variable while everything else are assumed constant.
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities.
Answer:
D. They run from north to south
The quote from the Gettysburg Address details how Lincoln used phrases in his speech to remind his listeners of the American ideals of liberty, equality, and the responsibility of government. Lincoln asserts to the people that it is their duty as survivors of fallen soldiers to uphold the ideals that they gave their lives for. Lincoln also cites religion, "...under God..." to support the idea of freedom and liberty for all people. He also defends the idea of the people and government having the responsibility to ensure that the government is representative of the wants and needs of the citizens, "...government of the people, by the people..."
