The meaning of ALARA in radiation?

Which of these is most likely to happen if parallax measurements of star distances are taken after a gap of six months? the results would be accurate the results would be inconsistent the results would not be valid the results would not be repeated

Which chemical reaction shows photosynthesis? a. water + carbon dioxide + sunlight → oxygen + glucose b. carbon + oxygen → carbon dioxide c. hydrogen + oxygen → water d. nitrogen + hydrogen → ammonia

The changes that the students observed, rapid breathing and sweating, would be classified as a to a change in a system.