Which of the following best defines spring constant ? a. the amount of force needed to extend or compression of a spring for every 1 kilogram of the spring.
b. the amount of force needed every 1 meter of stretch or compression of the spring.
c. the amount of energy needed to extend or compress a spring for every 1 kilogram of mass of the spring.
d. the amount of energy needed for every 1 meter of stretch or compression of the spring. ​