Answer:
1 ) D. oxidation processes results in the reddish orange coating metal (rust).
2 ) D. sinkhole is formed by the collapse of caves .
3 ) The largest area of karst in the United States is included in C. Florida
Explanation:
1 ) Oxidation -
Oxidation is the process that causes the metal to rust , in presence of moist air . This weathering process is also useful in the cave formation
2) Sinkhole -
Sinkhole is a hole in the ground which is formed when both rocks and soil are removed by flowing water .
3) Florida -
Florida includes the largest area of karst in the United States .