The isotherms of a gas are shown below:
Among the following:
$(i)$ At $T_1$,the gas cannot be liquefied.
$(ii)$ At point $B$,liquid starts to appear at $T_2$.
$(iii)$ $T_c$ is the highest temperature at which the gas can be liquefied.
$(iv)$ At point $A$,a small increase in pressure condenses the whole system to a liquid.
The correct statements are:

• A
  only $(i)$ and $(ii)$
• B
  only $(i), (iii)$ and $(iv)$
• C
  only $(ii), (iii)$ and $(iv)$
• D
  $(i), (ii), (iii)$ and $(iv)$