What is the horizontal asymptote of g(x) = -(2)^(x)?

1. What is the horizontal asymptote of g(x) = -(2)^(x)?
a. y = 2
b. y = 0
c. y = -1
d. x = 0
2. What transformation changes f(x) = 4^x into g(x) = (1/3)(4)^(x-2)?
a. Shift left 3 units
b. Vertical compression by a factor of 1/3
c. Vertical stretch by a factor of 3
d. Shift down 3 units
3. What is the horizontal asymptote of g(x) = 4^x - 6?
a. y = -6
b. y = 0
c. y = 4
d. x = -6