Excavation, when approaching facilities, can be done using both mechanical and manual methods depending on the situation. Mechanical excavation is efficient for large projects, while manual excavation is suitable for detailed work in confined spaces. Hence, the answer to the question is 'C. Both of them.' ;
Excavation can be performed using both mechanical and manual methods depending on the context, with mechanical methods being faster for large areas and manual methods allowing for precision in sensitive environments. Thus, the answer is 'C. Both of them.'
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