Which of the following is a substance that acts at a long distance from the site at which it is secreted? a) local regulator b) hormone paracrine c) signal neurotransmitter d) synaptic signal

Option B , hormone paracrine

Explanation:

All the signals that are released from hormones usually act on some distant site.  

Endocrine signals releases hormones that act on target cell at large distances. These large distance signals move to the target cell through bloodstream. However, transmission through body fluid is a slow process.  

Endocrine glands such as  thyroid gland etc. release ligands that are  produced in one part of the body but affect other body regions some distance away.

Thus option B is correct

photosynthesis makes the glucose that is used in cellular respiration to make atp. the glucose is then turned back into carbon dioxide, which is used in photosynthesis. while water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.