The fourth event took place in the "Grand Canyon's" geologic history was "Dox Sandstone is deposited in a beach environment".
Option: B
Step-by-step explanation:
The geological history of Grand Canyon located in Arizona, USA and involve full-sequenced rock studies on Earth. This arrangement is studied in the form of “ Unkar Group”, involve a layer of sedimentary rock named as “Stratum” from Proterozoic age which is branched into five geologic formations. This process is arranged in the following increasing order: Bass formation > Hakatai Shale > Shinumo Quartzite > Dox Formation > Cardenas Basalt. Here Dox formation is 4th portion which took place in Grand Canyon’s origination, which is a sandstone from Mesoproterozoic rock.