Hint: Conjunctions are words that link other words, phrases or clauses together. For example: and, nor, but, yet and so etc.
Option A) Unless – is the correct answer because unless is a subordinating conjunction. Subordinating conjunction is a word that connects independent clauses to dependent clauses. So, unless is the best fit in the sentence because it shows the connection of independent clause on dependent clause and also, we use unless when there may be an exception and this exception will change the situation. Thus, this is the correct answer.
Option B) Although – is an incorrect answer because the meaning of although is ‘in spite of the fact that’ thus, this option can be ruled out. Thus, this is an incorrect answer
Option C) As if – is an incorrect answer because the meaning of ‘as if’ is used to define how something seems from the information given. Thus, use of ‘as if’ in the blank is inappropriate. Thus, this is an incorrect answer.
Option D) Or – is an incorrect answer because ‘or’ is used to indicate that there is a choice and one person is suppose to choose from the options while in the sentence it is clearly portrayed that you can only cast your vote in a particular situation which is if you show your voting card i.e. there are no other alternatives given. Thus, this is an incorrect answer.
Hence, the correct answer is Option ‘ A’.
Note: There are four types of conjunctions i.e. coordinating, correlative, subordinate and adverbial conjunctions. In this question, subordinating conjunction is used to connect independent clauses to dependent clauses. Other examples of subordinating conjunctions: before, since, unless, until after etc. Coordinating conjunctions: and, but, for, or so etc. Correlative conjunctions: not only – but also, neither – nor, either – or. Adverbial conjunctions: however, otherwise, therefore, instead. So, Option A is the most appropriate answer as compared to any other option.