Greetings from Brasil...
In a trigonometric function
F(X) = ±UD ± A.COS(Px + LR)
UD - move the graph to Up or Down (+ = up | - = down)
A - amplitude
P - period (period = 2Ï€/P)
LR - move the graph to Left or Right (+ = left | - = right)
So:
A) F(X) = COS(X + 1)
standard cosine graph with 1 unit shift to the left
B) F(X) = COS(X) - 1 = -1 + COS(X)
standard cosine graph with 1 unit down
C) F(X) = COS(X - 1)
standard cosine graph with shift 1 unit to the right
D) F(X) = SEN(X - 1)
standard Sine graph with shift 1 unit to the right
Observing the graph we notice the sine function shifted 1 unit to the right, then
Option D
(cosine star the curve in X and Y = zero. sine start the curve in Y = 1)