When Coach Kwan notices that a player is getting tired, she takes out the tired player and substitutes a fresh player. Which type of chemical reaction does this best model?

Single replacement Reaction

Explanation:

A replacement reaction is a  chemical reaction in which an  element replaces another element  in a compound especially when it is more reactive than the former. There are two types of replacement reaction, the single and double replacement reaction.

In the former, one  element which  is usually more reactive than the other replaces it . For example in the single replacement, a more reactive metal replaces a less reactive metal and also a more reactive non metal can replace a less reactive non metal.

A + BC → B + AC

looking at the equation aove, you can see that B replaces A

Also In double replacement, the elements in the both reacting compounds are replaced or exchanged to form new compounds as can be illustrated in the equation

AB + CD —— AC + BD

In the case of Coach Kwan, she follows the Single  replacement model as she substitutes a less active and tired player with an active one.  

i think it's c. if you look search electronic symbol on google and then click on wiki it shows you a