Ray L. Zapp is thinking about testing strategies for his new HashTable class, which uses Rainforest's cloud storage service to make hash tables persistent. For the next 4 questions, write the letter of the one BEST testing technique (from the list below) to achieve the listed testing goal. (Some testing techniques may be used more than once or not at all.) A. Black-box testing B. Fuzz testing C. Stubbing& mocking D. Mutation testing E. White-box/glass-box testing 4 13.(1 pts) Making sure the hash table is robust when presented with nonsensical input 15. (1 pts) Making sure his service behaves correctly when Rainforest's cloud storage service is down 16. (1 pts) Improving the thoroughness of coverage of his test suite by uncovering test cases he missed 一( 1 pts) Making sure hash collisions are handled properly