Let \(\left(B_{t}ight)_{t \in \mathbb{R}_{+}}\)denote a standard Brownian motion. Let \(c>0\). Among the following processes, tell which is a standard Brownian motion and which is not. Justify your answer.

a) \(\left(X_{t}ight)_{t \in \mathbb{R}_{+}}:=\left(B_{c+t}-B_{c}ight)_{t \in \mathbb{R}_{+}}\),

b) \(\left(X_{t}ight)_{t \in \mathbb{R}_{+}}:=\left(B_{c t^{2}}ight)_{t \in \mathbb{R}_{+}}\),

c) \(\left(X_{t}ight)_{t \in \mathbb{R}_{+}}:=\left(c B_{t / c^{2}}ight)_{t \in \mathbb{R}_{+}}\),

d) \(\left(X_{t}ight)_{t \in \mathbb{R}_{+}}:=\left(B_{t}+B_{t / 2}ight)_{t \in \mathbb{R}_{+}}\).