Which material that was formerly on the bottom of lake bonneville is most likely exposed on the land surface today

Question: The map below shows the area that, at one time, was covered by ancient Lake Bonneville. Evidence of ancient shorelines indicates that, near the end of the last ice age, Lake Bonneville existed in western Utah and eastern Nevada. The Great Salt Lake in Utah is a remnant of the former Lake Bonneville. Which material that was formerly on the bottom of Lake Bonneville is most likely exposed on the land surface today?

(1) folded metamorphic bedrock

(2) flat-lying evaporite deposits

(3) coarse-grained coal beds

(4) fine-grained layers of volcanic lava

2) flat-lying evaporite deposits

a and b sometimes have a positive value

no. dot product   =0 when vecs at right angles