Many Students may have doubt why E is wrong:
Explanation from here:If a comparison allows for more than one reasonable interpretation, eliminate the answer choice.
E can be interpreted as follows:
Rice has a protein [that is] higher in quality than wheat [is high in quality].
Rice has a protein higher in quality than wheat [has a protein high in quality].
Since both of these interpretations are reasonable -- and an alternate choice offers a comparison that CANNOT be misinterpreted -- eliminate E.
Another problem:
Generally, a COMMA + with modifier serves to modify the nearest preceding clause.
Your interpretation of E:
Rice has a protein higher in quality than wheat [has a protein high in quality], with more of the amino acids essential to the human diet.
Here, with more of the amino acids seems to be modifying the implied clause in red -- the nearest preceding clause - implying that WHEAT has a protein with more of the amino acids essential to the human diet.
The intended meaning is that RICE has a protein with more of the amino acids essential to the human diet.
One more issue:
E: protein higher in quality
Here, higher serves to modify protein, implying that the PROTEIN itself is higher.
The intended meaning is that the QUALITY of the protein is higher.
This meaning is more accurately conveyed by the wording in the OA:
protein of HIGHER QUALITY.