Final answer:
The Second Continental Congress made several pivotal decisions including sending the Olive Branch Petition, electing George Washington as Commander in Chief, forming the Continental Army, and issuing the Declaration of Independence. All options are correct.
Step-by-step explanation:
The decisions made by the Second Continental Congress included several significant actions which were foundational to the American Revolution and the foundation of the United States.
A) Sending the Olive Branch Petition to King George III was indeed one of the last efforts at peace, proposing either free trade and taxes equal to those living in Great Britain or no taxes at all.
B) Electing George Washington as Commander in Chief of the newly formed Continental Army was a decisive military move that laid the groundwork for the Revolutionary War.
C) Forming the Continental Army was necessary to defend the rights and liberties of the colonists against British aggression.
D) Issuing the Declaration of Independence was a later action by the Congress, formally adopting it on July 4, 1776, and marking the legal separation of the 13 colonies from Great Britain.
Therefore, all the options provided (A, B, C, and D) were decisions made by the Second Continental Congress at various stages of its existence. All options are correct.