Step 1: Understanding the Problem:
Plants assimilate inorganic nitrogen (ammonia) into organic compounds through biochemical pathways.
The question mentions "reductive deamination", which is a common typographical error in exam papers; the correct biological term intended is reductive amination.
Step 2: Approach and Formula:
Analyze each given chemical equation to identify the characteristic components of reductive amination: a keto acid reacting with ammonia using a reducing agent (like NADPH/NADH).
Step 3: Detailed Explanation:
Let's review the provided options carefully:
Option (A) shows ammonia (\(NH_4^+\)) reacting with \(\alpha\)-ketoglutaric acid in the presence of a reducing agent (\(NADPH_2\)) to produce Glutamic acid.
This is the classic textbook equation for reductive amination catalyzed by the enzyme glutamate dehydrogenase.
Option (B) represents the transfer of an amino group from Glutamic acid to Oxaloacetic acid, which is defined as transamination.
Options (C) and (D) describe the ATP-driven addition of an extra amino group to an amino acid to form amides (Glutamine and Asparagine), a process known as amidation.
Step 4: Final Answer:
Option (A) accurately depicts the intended process of reductive amination.