Why can Jamaica change the lineup for the 4x100?

Question

Why can Jamaica change the lineup for the 4x100?

Answer 1

If they win a medal which I believe they will, how many medals are going to be handed out, six or just four?  

Answer 2

cause everybody has that luxury, so why cant the Jamaicans?

Answer 3

Because they have alot to choose from.

Answer 4

all the countries that qualify for the final can...

just like in the swimming....

a country will often 'rest' one or two of the  better athletes if they feel certain of making the final....

Answer 5

Teams can nominate six runners, and use any four of them in the heats and the final.

Answer 6

US has 95 medals  Jamaica has 7. Stop crying.  The Jamaicans are better sprinters, deal with it.  There is enough in the world for everyone, did you not learn to share in school?.