The yellow rust of wheat is caused by

✅ Explanation:Yellow rust, also known as stripe rust, is a fungal disease that affects wheat crops worldwide. It is caused by the pathogen Puccinia striiformis. The disease is characterized by the appearance of yellow stripes on the leaves of wheat plants, which can significantly reduce yield.

📌 Other Options Explanations:
-(b) Puccinia recondita: This fungus causes leaf rust or brown rust of wheat.
-(c) P. graminis tritici: This fungus causes stem rust or black rust of wheat.
-(d) Puccinia hordei: This fungus causes leaf rust of barley.