Which component is crucial for network connectivity?

The Network Interface Card (NIC) is essential for network connectivity because it serves as the hardware interface between a computer or other device and the network. The NIC converts data from the device into a format suitable for transmission over the network and vice versa. This capability allows the device to communicate with other devices on the same network or across the internet.

Without a NIC, the device wouldn't have the means to connect to a network, making it impossible to send or receive data. This component can be integrated into the motherboard or exist as an external add-on card. By facilitating this connection, the NIC plays a vital role in enabling network communication, making it the most crucial component among the options provided.

In contrast, while the CPU and RAM are integral for processing data and managing system resources, they do not directly facilitate network connections. The HDD, which is used for storing data, also does not play a role in maintaining network connectivity, as it is focused on data storage rather than data transmission.