Call Option
The first thing a call option refers to is the right of someone who has issued a bond to redeem it at the current value (which implicitly implies that it is before the actualy maturity date).
Secondly, it could be a particular type of agreement that allows a buyer the right to purchase a financial product (such as a currency for instance) at a particular price that is agreed. This is known as the exercise price, for obvious reasons.
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