Anyone have an idea?

 option C.)   an 1.2 (n-1) -5  Sorry, no subscript for "a sub n"

Step-by-step explanation:

Substitute the values of n 1,2,3,4 and see if the output is the corresponding number in the sequence.

n = 1      2     3      4

   -5   -3.8  -2.6  -1.4

an=  1.2 (n-1) -5    the n-1 needs to be a number multiplied  by 1.2 produces a number added to -5 results in the number in the sequence.

a1=1.2(1-1) -5   a= 1.2(0) -5  a= -5

a2 1.2 (2-1) -5   a= 1.2(1) -5  a= -1.2 -5  a= -3.8

a3 1.2 (3-1) -5   a= 1.2(2) -5  a= -2.4 -5  a= -2.6

a4 1.2 (4-1) -5   a= 1.2(3) -5  a= -3.6 -5  a= -1.4

1. minimum

2. 6400

3. eight

hope this !