On August 1, 2011, Mars was easily visible from Earth between a. 9:00 pm to midnight.
b. sunset to sunrise.
c. 3:00 am and 3:00 pm.
d. 3:00 am to sunrise.​

Iwould say d. eye contact and body language because you aren’t using any spoken communication. hope this : )

So  if  the sum of the enthalpies of the reactants is greater than the products, the  reaction  will be  exothermic.  if  the products side has a larger enthalpy, the  reaction  is  endothermic. you may wonder why  endothermic reactions, which soak up energy or enthalpy from the environment, even happen