Why there is no boot option in BIOS?

Go to Security tab and disable Safe boot. Grab a Windows disk and put it in. Restart the computer and hold in ESC. You will come up to a Blue box and from there you just choose your Windows Disc.

Where is boot mode in BIOS?

Power on system. Press F2 when prompted to enter BIOS menu. Navigate to Boot Maintenance Manager -> Advanced Boot Options -> Boot Mode. Select the desired mode: UEFI or Legacy.