Assertion : Fundamental frequency of a narrow organ pipe is more...

Assertion: True. For the same physical length $L$, a narrow pipe has smaller end correction than a broad pipe, so its effective length (L_{\text{eff }}=L+e) is smaller and therefore its fundamental frequency (f \propto 1 / L_{\text{eff }}) is larger. Reason: False. Applying end correction increases the effective length, so the actual fundamental frequency is less than $v /(4 L)$, not more. The Reason's statement is therefore incorrect.