Which is the smallest fraction in $$\frac{2020}{2021}$$, $$\frac{2021}{2022}$$, $$\frac{2022}{2023}$$ and $$\frac{2023}{2024}$$? 
选项为:A:$$\frac{2020}{2021}$$  B:$$\frac{2021}{2022}$$  C:$$\frac{2022}{2023}$$  D:$$\frac{2023}{2024}$$  请回答其中一个选项.