With respect to the conformers of ethane, which of the following statements is true ?

Question

$\begin{array}{1 1} (1)\text{Bond angle remains same but bond length changes}\\ (2) \text{Bond angle changes but bond length remains same} \\ (3) \text{Both bond angle and bond length change} \\ \text{(4) Both bond angles and bond length remains same} \end{array}$