echo -n "Enter A, B or C: "
read letter
letter=$(echo $letter | tr '[a-z]' '[A-Z]')
case "$letter" in
	A)
	echo "You entered A"
	;;
	B)
	echo "You entered B"
	;;
	C)
	echo "You entered C"
	;;
	*)
	echo "You did not enter A, B, C"
	;;
esac