Concept:
Ustad Mansur was one of the greatest painters in Emperor Jahangir's court and was renowned for his extraordinarily accurate paintings of birds, animals, and plants. Jahangir, who had a keen interest in nature and wildlife, conferred upon him the title of “Nadir-ul-Asr” (Wonder of the Age).
The painting Falcon on a Bird Rest is one of the celebrated examples of Ustad Mansur's mastery in naturalistic painting. His works are distinguished by meticulous observation, scientific precision, and lifelike representation.
Step 1: Recall the artist associated with “Falcon on a Bird Rest”.
The painting Falcon on a Bird Rest belongs to the Mughal period during the reign of Jahangir and was painted by Ustad Mansur.
\[
\boxed{\textit{Falcon on a Bird Rest} \Longrightarrow \text{Ustad Mansur}}
\]
Step 2: Examine the given options.
• Ustad Mansur -- Famous Mughal painter specializing in birds, animals, and natural history subjects.
• Daswant -- Eminent painter of Emperor Akbar's court.
• Sayyid Ali -- Persian painter who worked in Humayun's and Akbar's courts.
• Guman -- Rajput painter, not associated with Jahangir's natural history paintings.
Hence,
\[
\boxed{\text{(A) Ustad Mansur}}
\]