Which of the following statements is correct?

Earth's orbit is circular.
Earth is the only planet with an elliptical orbit.
Earth's orbit is elliptical.

Physical needs include: a. the need for sleep b. the need to feel safe c. the need to feel secure d. all of the above

The difference of sample means of two populations is 55.4, and the standard deviation of the difference of sample means is 28.1. which statement is true if we are testing the null hypothesis at the 95% confidence level? a. the difference of the two means is significant, so the null hypothesis must be rejected. b. the difference of the two means is significant, so the null hypothesis must be accepted. c. the difference of the two means is not significant, so the null hypothesis must be rejected. d. the difference of the two means is not significant, so the null hypothesis must be accepted.

50 points i think its melatonin because its a hormone but im not sure