Mr. Tang has a Hong Kong employment with Longtime Ltd. On 1 July 2020, Mr. Tang was granted 10,000 shares by Longtime Ltd., subject to a vesting period of two years. The 10,000 shares were fully vested on 1 July 2022. He sold 5,000 shares on 30 November 2022. The market values of the shares were $10 on 1 August 2020, $20 on 1 July 2022, and $25 on 30 November 2022. 

What is the taxable amount when Mr. Tang sold his shares? 

a. $225,000. 

b. $100,000. 

c. $0. 

d. $250,000