阅读下面短文，掌握其大意，然后从各题所给的四个选项中选出可以填入空白处的最佳选项。

There are four seasons in a year, and my favourite ___ is autumn. The weather is neither too hot nor too cold, and the sky is always ___ and blue. The fields turn golden and the farmers are busy ___ in the harvest. I often go for a walk with my parents in the countryside at weekends. The fresh air and the beautiful views make me ___(4) quite relaxed. That is why I ___ autumn best of all the seasons.

【第4空】