How Does the Delta of an In-the-Money Call Option Change as It Approaches Expiration?

As an in-the-money (ITM) call option approaches expiration, its delta will approach 1.0. This is because an ITM option is highly likely to finish ITM, meaning its price movement will nearly perfectly mirror the price movement of the underlying asset.

The option behaves almost exactly like holding the underlying asset itself, hence the delta converges to its maximum value.