Which of the following commands overwrites the bootloader located on /dev/sda without overwriting the partition table or any data following it?

`dd if=/dev/zero of=/dev/sda bs=512` without a `count` will overwrite the entire `/dev/sda` with zeros, including the partition table and all data.

`dd if=/dev/zero of=/dev/sda bs=512 count=1` overwrites the entire 512-byte MBR, including both the bootloader and the partition table, which is not desired.

The MBR contains the bootloader code (first 440 bytes) and the partition table (next 64 bytes). Using `dd if=/dev/zero of=/dev/sda bs=440 count=1` writes 440 bytes of zeros from `if=/dev/zero` to the beginning of `/dev/sda`, effectively wiping only the bootloader code while preserving the partition table and other data.

`dd if=/dev/zero of=/dev/sda bs=440` without a `count` will continuously write 440-byte blocks of zeros until the input stream (`/dev/zero`) is exhausted or interrupted, effectively overwriting the entire disk.