Choose the correct passive form of past tense from the options given below:
Mallika {Fill_Regular} the house captain by all.

The structure that will help us in chancing the right answer is – there has to be an applicable form of the verb – to be once participle form. 
So, keeping the over mentioned conditions in mind let us look into the different options and try and understand which will be the correct unresistant form of once tense for the below given judgment . 
Now Coming to the Options Given in the Questions:
Chose – it's the simple once tense form of the verb' to choose'. It's also in the active voice. We can see in the question that the needed form for a correct result is of unresistant voice which this is not. 
Chosen is a once participle which requires a helping verb – was, so as to help determine the tense. Without this helping verb, the judgment sounds incorrect. 
Was chosen – has the simple once form of the verb ‘ to be', i.e. was. ‘ Was chosen' is the required structure, which is formed by the history tense verb' was' once participle( chosen). 
Were chosen-' In this option Were' is for of Plural verb whereas the subject Mallika is singular. The subject and verb must agree with one another in terms of number. 
So, as you can see that the correct option is the option – c, as it fulfills the conditions to be the correct unresistant form.