Usage of Comma

Directions: Find the sentence/part of the sentence having an error/errors with regard to the usage of a comma.

(i) Buddhism has at its heart the wisdom of understanding the mind.
(ii) From Buddhism and other Eastern spiritual traditions, we know that there are two main types of life force energy: internal and external.
(iii) External life force energy exists within plants, flowers, trees, rocks, minerals, crystals, etc.