Final answer:
Dalits were considered "untouchable" and "unseeable" because they were perceived as spiritually impure.
Step-by-step explanation:
The statement that explains why Dalits were considered to be "untouchable" and "unseeable" is option b: They were perceived as spiritually impure.
The Dalits were traditionally assigned jobs related to "polluting activities," which were seen as spiritually impure by the higher castes. They were also restricted from entering Hindu places of worship and drinking water from the same sources as higher castes. These discriminatory practices were based on the belief that the Dalits' presence would contaminate the purity of the higher castes.