In the context of the skin senses, when warm and cold receptors that are close to each other in the skin are stimulated simultaneously, a person experiences the sensation of hotness coldness hotness and coldness neither hotness nor coldness

The correct answer is option A " hotness"

The receptors either hot or cold receptor produces electrical signals whenever there is an external stimulus in the form of temperature change.  

In the case of thermo receptors which are activated by heat condition, the rate of signaling increases which in turn produces warm feeling while in case of thermo receptors which are activated by cold condition, the rate of signal reduces and the rate of firing increase and this stimulates cold feeling. Thus, when the two receptors are stimulated simultaneously, the fast signaling due to activation by heat has a faster rate of increasing the signal as compared to the activation by cold.  

all matter is made up of atoms

in any element all atoms are the same

elements in a compound are always in a constant ratio: apex