To prepare a Lemon soufflé, a series of steps need to be followed in the correct sequence to ensure the dessert is creamy and light. Let's break down the sequence of steps:

1. Separate the yolk of egg from the white (d): Start by separating the egg yolk from the egg white, as they are used differently in the recipe.
2. Add sugar and lemon extract to egg yolk (c): Combine sugar and lemon extract with the egg yolk to add sweetness and flavor.
3. Whisk the egg yolk mixture in a double boiler till creamy (f): Heat and whisk the mixture in a double boiler to achieve a creamy consistency.
4. Remove from double boiler and cool (a): Once creamy, remove the mixture from heat to cool down before adding other ingredients.
5. Add dissolved gelatin gradually to the egg yolk mixture and cool (b): Dissolve gelatin separately and gradually blend it with the cooled egg yolk mixture for structure.
6. Fold in the whipped egg white and cream to the cooled egg mixture (e): Gently fold in the whipped egg whites and cream to incorporate air and give the soufflé its light texture.
7. Set the mixture in a soufflé dish in the refrigerator (g): Finally, place the mixture into a soufflé dish and allow it to set in the refrigerator, which helps the soufflé hold its shape.

The correct sequence of operations is indeed (d), (c), (f), (a), (b), (e), (g). This sequence ensures that the soufflé is prepared with the right texture and flavor.