Swap 2 arrays in matlab

i am trying to swap 2 arrays inside an array for example

a= [1 2 3];

b=[ 5 3];

c=[ 9 3 7 6];

d=[ 7 5];

X1= [ a, b , d, c ];

now i want to swap any 2 random arrays inside X1 , knowing that each array have its own size.