In the given pentapeptide, find out an essential amino acid $(Y)$ and the sequence present in the pentapeptide: Choose the correct answer from the options given below:

• A
  $(Y) = \text{Threonine}, (\text{Sequence}) = \text{Ser} - \text{Thr} - \text{Asp} - \text{Gly} - \text{Ala}$
• B
  $(Y) = \text{Serine}, (\text{Sequence}) = \text{Thr} - \text{Ser} - \text{Asp} - \text{Ala} - \text{Gly}$
• C
  $(Y) = \text{Threonine}, (\text{Sequence}) = \text{Thr} - \text{Ser} - \text{Asp} - \text{Gly} - \text{Ala}$
• D
  $(Y) = \text{Serine}, (\text{Sequence}) = \text{Ser} - \text{Asp} - \text{Thr} - \text{Ala} - \text{Gly}$