Which carbocation is the most stable?

Identify the correct sequence for True and False.
$(I)$ Only compounds with chiral centers can be optically active.
$(II)$ Absence of elements of symmetry is the reason for a molecule's optical activity.
$(III)$ All organic compounds contain carbon $\&$ hydrogen.
$(IV)$ Different canonical forms of a molecule represent the actual structures of a molecule which has resonance in it.

Which of the following is isomeric with methyl vinyl ether?

Which is the correct structure of $D$-glyceraldehyde?

Which statement regarding the following structures is true?

Determine the absolute configurations of the labeled carbons ($a$ and $b$).