Free nerve endings in the skin detect changes in skin temperature (getting warmer).

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

i would say b

explanation:

but i think i would need more information than that

28528289 29823282 8298232 39858

16

explanation:

the marks go by 4s