C#: using System;

class FlexibleArrayMethod

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static void Main$()$

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$//$ Declare three integer arrays of different sizes

int$[]$ array$1=\{1,2,3,4,5\}$;

int$[]$ array$2=\{6,7,8\}$;

int$[]$ array$3=\{9,10,11,12\}$;

$//$ Pass each array to the DisplayAndSum method

DisplayAndSum$($array$1)$;

DisplayAndSum$($array$2)$;

DisplayAndSum$($array$3)$;

$\}$

$//$ Method to display array elements and their sum

static void DisplayAndSum$($int$[]$ array$)$

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int sum $=0$;

Console.Write$("$Array Elements: $")$;

foreach $($int element in array$)$

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Console.Write$($element $+"")$;

sum $+=$ element;

$\}$

Console.WriteLine$("$

Sum of Array Elements: $"+$ sum$)$;

Console.WriteLine$()$; $//$ For better readability

$\}$

$\}$