Two orthogonal signals $$s_1(t)$$ and $$s_2(t)$$ satisfy the following relation

A

$$\int_{0}^{T} S_1(t)S_2(t)dt = 0$$

B

$$\int_{0}^{T} S_1(t)S_2(t)dt = 1$$

C

$$\int_{0}^{T} S_1(t)S_2(t)dt = \infty$$

D

$$\int_{0}^{T} S_1(t)S_2(t)dt = \pi$$