Proportional representation is a system in which the number of seats a party gains in a legislature is in proportion to the number of votes it receives. It allows for a more accurate representation of the public`s voting preferences.

Option 1: This option doesn`t disqualify the necessity for proportional representation as the presence or absence of reserved constituencies doesn`t directly relate to how votes are distributed.

Option 2: In a two-party system, the winner usually takes all the representation, making proportional representation unnecessary. Because there are only two main parties, the party with the most votes effectively represents the majority of voters, albeit it doesn`t totally encapsulate all voters` preferences.

Option 3: The first-past-post system is basically a winner-takes-all system but this doesn`t rule out the necessity for proportional representation particularly in multi-party systems where diverse views need to be represented.

Option 4: The fusion of Presidential and Parliamentary forms of governments is about forms of governance rather than voting systems. So, it doesn`t automatically make proportional representation unnecessary.