Pick out the true statements.

Pick out the true statements.

Pick out the true statements.
a. Let $f : \mathbb Z\to \mathbb Z^2$ be a bijection. There exists a
continuous function from $\mathbb R$ to $\mathbb R^2$ which extends $f.$
b. Let $D$ denote the closed unit disc in $\mathbb R^2.$ There exists a
continuous mapping $f : D-\{(0, 0)\}$$\to \{x\in R : |x|\le1\}$ which is
onto.
c. Let $D$ denote the closed unit disc in $\mathbb R^2.$ There exists a
continuous mapping $f : D-\{(0, 0)\}$$\to\{x\in R : |x|>1\}$ which is
onto.
Should I use Uryshon Lemman/Tietze Extension?