How to get the OS selection menu on boot?

Question

linux

Worth Win10. I put Ubuntu on a separate disk, I can’t boot it (regardless of the selected hard disk in the boot order dialog, windows is loaded).
I googled that GRUB is needed, which, apparently, did not register in the MBR.
I ask for help with determining the root partition and installing GRUB into it.
Partition information:

NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 931.5G  0 disk 
├─sda1   8:1    0 670.7G  0 part 
└─sda2   8:2    0 260.8G  0 part 
sdb      8:16   0 111.8G  0 disk 
├─sdb1   8:17   0   7.8G  0 part [SWAP]
└─sdb2   8:18   0   102G  0 part 
sdc      8:32   0   1.8T  0 disk 
└─sdc1   8:33   0   1.8T  0 part 
sdd      8:48   0 465.8G  0 disk 
├─sdd1   8:49   0 146.5G  0 part 
└─sdd2   8:50   0 319.3G  0 part 
sde      8:64   0 111.8G  0 disk 
└─sde1   8:65   0 111.8G  0 part 
sdf      8:80   1   7.4G  0 disk 
└─sdf1   8:81   1   7.4G  0 part /cdrom
sdj      8:144  0   1.8T  0 disk 
└─sdj1   8:145  0   1.8T  0 part /media/ubuntu/Elements
loop0    7:0    0 962.1M  1 loop /rofs
[email protected]:~$ blkid
/dev/loop0: TYPE="squashfs" 
/dev/sda1: LABEL="Media" UUID="C131661523341467" TYPE="ntfs" 
/dev/sda2: LABEL="BackUps" UUID="CAE04D19E04D0D5F" TYPE="ntfs" 
/dev/sdb1: UUID="af19cd97-b7b2-47c7-8d22-aba7718b9b47" TYPE="swap" 
/dev/sdb2: UUID="8e83afa2-c7b0-4822-9353-02692bd90786" TYPE="ext4" 
/dev/sdc1: LABEL="Foto" UUID="94ACD87DACD85B76" TYPE="ntfs" 
/dev/sdd1: LABEL="Work" UUID="281477001476D074" TYPE="ntfs" 
/dev/sdd2: LABEL="Downloads" UUID="4A468B7B468B6693" TYPE="ntfs" 
/dev/sde1: LABEL="Windows_10" UUID="481A78751A7861BC" TYPE="ntfs" 
/dev/sdf1: LABEL="TRANSCEND" UUID="60A4-3567" TYPE="vfat" 
/dev/sdj1: LABEL="Elements" UUID="4E84E9E384E9CE11" TYPE="ntfs"

Answer 1

grub-install /dev/sdX, where /dev/sdX is the drive you want to put it on (it must be configured in BIOS Setup as the drive from which you want to boot).
If you can't boot into the Linux installed, then you can boot from the Live CD/flash drive, enroll in the installed riot, and run the command above.
Generally, man grub-install.

Answer 2

Attention!
If you have Win10, then grub can break the boot. Especially if there is UEFI.
A religiously correct option is to use the bcdedit utility in Windows itself,