The correct option is A See
'Seek' is the base form of the verb, its past and past participle form is 'sought'.
Therefore, option D 'seek' is incorrect.
'See' is the base form of the verb and since it is an irregular verb its past form is 'saw' and its past participle form is 'seen'.
Therefore, option B 'saw' is an incorrect option whereas, seeing is the continuous form of the verb 'see', therefore option C is incorrect.
The correct option is option A.