The correct answer is option 4: "It is the highest civilian award of the United States of America." This statement is not correct. The Legion of Merit is not the highest civilian award of the United States of America.

Option 1 states that the Legion of Merit award is conferred by the President of the United States of America. This is correct. The President has the authority to confer this award to individuals in recognition of exceptional service or achievements.

Option 2 states that this award was conferred to the Prime Minister of India in December 2020. This is correct. In December 2020, the Prime Minister of India, Narendra Modi, was presented with the Legion of Merit by the United States government for his leadership and strengthening of the US-India strategic partnership.

Option 3 states that the Legion of Merit was also awarded to the Prime Minister of Australia, Scott Morrison. This is correct. In December 2020, Scott Morrison was also awarded the Legion of Merit for his leadership in addressing global challenges and advancing Australia`s security and defense partnership with the United States.

Therefore, option 4 is the statement that is not correct. The Legion of Merit is not the highest civilian award of the United States of America.