A sentence is usually in active voice, when the subject performs an action toward an object. When the sentence is changed to passive voice, the object takes the position of the subject, such that the meaning is maintained.
For example: I helped you. (Active voice)
                       You were helped by me. (Passive voice)
The verb that 'expresses the action (helped) done by the subject (I)' is in the active voice.
The verb that expresses what is done to the subject is in the passive voice.
The given sentence is in passive voice; Damian is the subject, 'was submitted by' is the verb in the passive form.
From the options, D is in the active voice: Damian is the subject that performs the action (submitted) toward the object (the application form). Hence D is correct.
Option A has changed in meaning 'was forced to'. Moreover, the sentence is still in passive form. It refers to an action carried out 'by' the subject whereas the active voice refers to the subject carrying out an action.
Similarly, option B has changed in meaning, 'took the decision' and 'because of his father's interest' are extensions that are not required. It is not mentioned in the main sentence about his decision, or his father's interest.
Option C has also changed in form: is responsible for his submission'. The verb 'submitted' has changed to a noun 'submission' and a new verb 'is' is introduced.
These options are not the active voice of the given sentence, hence A, B and C are incorrect.