Respuesta :

Answer: Choice C

We start with 8 and cut each term in half to get the next term
eg: 8*1/2 = 4
The common ratio is r = 1/2 found by taking any term and dividing it over its previous term
The common ratio r  is 4/8  =  1/2 and the first term a1  = 8

an = a1 * (1/2)^(r-1)

an = 8 (1/2)^(r-1)   which is choice C.