What is the total number of different types of unit cells present in the triclinic crystal system?

Which type of unit cell from the following is common to all seven types of crystal systems?

The crystal system of a compound with unit cell dimensions $a = 0.387 \ nm$,$b = 0.387 \ nm$ and $c = 0.504 \ nm$ and $\alpha = \beta = 90^{\circ}$ and $\gamma = 120^{\circ}$ is:

$Assertion (A)$: White tin is an example of a tetragonal system. $Reasoning (R)$: For a tetragonal system,$a=b=c$ and $\alpha=\beta=\gamma \neq 90^{\circ}$. The correct answer is

Which of the following crystal systems exists only as a primitive Bravais lattice?

The parameters $a = b = c$ and $\alpha = \beta = \gamma \neq 90^\circ$ belong to which crystal system?