Final answer:
Increasing the concentration of amino acid transport protein will decrease the transport affinity (Kt) of L-alanine. The option (B) is correct.
Step-by-step explanation:
Increasing the concentration of amino acid transport protein will decrease the transport affinity (Kt) of L-alanine. When the concentration of the transport protein is increased, more transporters are available to bind with the amino acid.
As a result, the affinity of the transport protein for the amino acid decreases, leading to a decrease in the transport affinity (Kt). This means that it will be more difficult for L-alanine to be transported into the cell. Therefore, the correct answer is B. decrease.