The correct option is
A ![](https://df0b18phdhzpx.cloudfront.net/ckeditor_assets/pictures/981035/original_08_1.png)
(a)
![](https://search-static.byjusweb.com/question-images/byjus/ckeditor_assets/pictures/981035/original_08_1.png)
1,3-cyclobutadiene is a cyclic, planar conjugated molecule having 4
π-electrons. Therefore, it is not an aromatic compound.
(b)
![](https://search-static.byjusweb.com/question-images/byjus/ckeditor_assets/pictures/981046/original_08_4.png)
Pyridine is a cyclic, planar conjugated molecule having 6
π-electrons. Therefore, it is an aromatic compound.
(Here lone pair of electrons of
N are not involved in delocalisation.)
(c)
![](https://search-static.byjusweb.com/question-images/byjus/ckeditor_assets/pictures/981047/original_08_5.png)
Furan is a cyclic, planar conjugated molecule having 6
π-electrons. Therefore, it is an aromatic compound.
(d)
![](https://search-static.byjusweb.com/question-images/byjus/ckeditor_assets/pictures/981049/original_08_6.png)
Thiophene is a cyclic, planar conjugated molecule having 6
π-electrons. Therefore, it is an aromatic compound.
Hence option (a) is correct.