What is Gibbs free energy?

Question

A. The energy lost as heat to the surrounding molecules
B. The usable energy released or absorbed by a reaction
C. The energy in the form of kinetic energy in a system
D. The energy contained within the bonds of molecules

Answer 1

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/helmholtz.html

Answer 2

or better:
https://www.boundless.com/biology/textbooks/boundless-biology-textbook/metabolism-6/potential-kinetic-free-and-activation-energy-69/free-energy-345-11482/

Answer 3

You do not need the s on https

http://www.boundless.com/biology/textbooks/boundless-biology-textbook/metabolism-6/potential-kinetic-free-and-activation-energy-69/free-energy-345-11482/