"One indication that some commonly observed physical change linked to age is a product of secondary aging is that ."

It does not occur in all adults

Explanation:

One indication that some commonly observed physical change linked to age is a product of secondary aging is that it does not occur in all adults

some commonly observed physical change that is most times linked to aging is classified as a product of secondary aging because they might not be seen on some adults whom might be of the same age bracket with people who manifest those physical changes and this is because of the differences in body types and in some cases due to the health status and lifestyle of the individuals

question - in 1827, john walker, a druggist in a small english town, tipped a splint with sulphur, chlorate of potash, and sulphid of antimony, and rubbed it on sandpaper, and it burst into flame. the druggist had discovered the first friction-chemical match, the kind we use to-day. it is called friction-chemical because it is made by mixing certain chemicals together and rubbing them. although walker's match did not require the bottle of acid, nevertheless it was not a good one. it could be lighted only by hard rubbing, and it sputtered and threw fire in all directions. in a few years, however, phosphorus was substituted on the tip for antimony, and the change worked wonders. the match could now be lighted with very little rubbing, and it was no longer necessary to have sandpaper upon which to rub it. it would ignite when rubbed on any dry surface, and there was no longer any sputtering. this was the phosphorus match, the match with which we are so familiar. according the paragraph what was the benefit of the new phosphorus match? it burst into flame when rubbed on sandpaper. it was made by mixing chemicals. it could be ignited on any dry surface. it threw fire in all directions.

answer - matches required natural chemicals

answer; delirium is a common adverse reaction seen when elderly patients take diphenhydramine;