Change the following statement into active voice: He was obliged to resign.

As the subject 'He' gets an action 'was obliged,' the sentence is written in the passive person.

If the subject of this statement is converted to active voice, the meaning of the sentence remains preserved.

As a result, the object replaces the subject and vice versa. The sentence's verb form is likewise altered from passive to active.

'Subject (He) + verb (was forced to resign) + infinitive (to resign)' becomes:

'New subject (circumstances) + verb (obligated) + new object (him) + infinitive (resign)'

In the simple past tense, the active form of 'was obliged' is 'obliged.' Because the passive form lacks an object, the object is implied in the sentence: He was forced to resign due to circumstances, with 'circumstances' understood to be the object.

As can be seen in option C, this is the correct answer.

Option A: Because'make' is not a past tense verb, the verb form 'was made to' is incorrect.

Option B: The sentence's structure has been altered. The verb "obliged" has been replaced with the noun "obligation."

Option D: Similarly, the verb form 'resign' has been transformed into the noun 'resignation.' The sentence's meaning has also changed.

As a result, alternatives A, B, and D are erroneous.