The alternate host of leaf rust of wheat is

Answer: Option A

The alternate host of leaf rust of wheat is Thalictrum.
Wheat leaf rust (Puccinia triticina) is a fungal disease that affects wheat, barley, rye stems, leaves and grains. P. triticina is heteroecious, requiring two distinct hosts (alternate hosts).
The alternate host for leaf rust (Puccinia triticina) is Thalictrum speciosissimum (meadow rue); and for crown rust (Puccinia coronate) is Rhamnus cathartica (buckthorn).