Which of the following has delocalised electrons?

Which of the following is aromatic?

The reaction sequence is as follows:
$1,4-dibromocyclohex-2-ene$ $\xrightarrow[{2 \, molar \, equivalent}]{{(CH_3)_2NH}} (A)$ $\xrightarrow{{BaO}} (B)$ $\xrightarrow[{ (2 \, molar \, equivalent) }]{{CH_3I}} (C)$ $\xrightarrow{{Ag_2O \, / \, H_2O}} (D) + 2(CH_3)_3N$
Identify the end product $(D)$ in the given sequence.

The product formed when acetylene is passed through a red-hot tube is:

Which one of these is not true for benzene?

The $C - C$ bond length in benzene is ...... $\mathring{A}$.