Who was the tenth Guru in Sikhism?

Guru Gobind Singh

The correct answer is Option 4 - Guru Gobind Singh

The tenth Guru in Sikhism is Guru Gobind Singh. He laid the foundation of the Khalsa Panth (army of the pure) and defined its five symbols: uncut hair, a dagger, a pair of shorts, a comb and a steel bangle. Under him the community got consolidated as a socio-religious and military force.

The ten Sikh Gurus in order are:

1. Guru Nanak Dev
2. Guru Angad Dev
3. Guru Amar Das
4. Guru Ram Das
5. Guru Arjan Dev
6. Guru Har Gobind Singh
7. Guru Har Rai
8. Guru Har Krishan
9. Guru Tegh Bahadur
10. Guru Gobind Singh