Which indicates the presence of oil in tar sands?
acids
bitumen
sandstone
shale
water

Bitumen

Explanation:

Tar sands, are sandstone deposits that majorly comprise of bitumen in about 10-20% proportion, 5% water and 80-85%  of other solid deposits. Bitumen which is a significant composition constituent of tar sands is a dark (or dark brown), extremely viscous material produced from refining of crude oil (petroleum) thereby making tar sands oily. As a  matter of fact, tar sands are also known as oil or bituminous sands.

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