Option 1 suggests that both the assertion and the reason are true and also the reason correctly explains the assertion. However, this is not valid as the reason statement is inaccurate.

Option 2 suggests that both the assertion and the reason are true but the reason doesn`t explain the assertion correctly. This is also not correct as the reason statement is false.

Option 3 states that the assertion is true, but the reason is false. This is the correct answer. It is a historical fact that Mohammed bin Tughlaq issued a new gold coin called Dinar. However, the reason provided for this event is incorrect. Mohammad bin Tughlaq introduced token currency in the form of brass and copper coins, not gold. The introduction of token currency was not specifically designed to promote trade with West Asian and North African countries.

Option 4 states that the assertion is false but the reason is true, which is incorrect. As explained earlier, the assertion is true and the reason is false.