21. A hospital ER needs to keep doctors on call, so that a qualified individual is available to perform every medical procedure that might be required (there is an ocial list of such procedures). For each of several doctors available for on-call duty, the additional salary they need to be paid, and which procedures they can perform, is known. The goal to choose doctors so that each procedure is covered, ata minimum cost. Is this problem in P-class? b. Is this problem in NP? c. Explain the reason of (b). (Yes or No or Not proved yet) (Yes or No or Not proved yet) a. d. Is this problem reducible from/to an NP-complete problem? (Yes or No) e. If Yes in (d), explain the reason with a reducing example. f. Is this problem in NP-complete or NP-hard? g. Explain the reason of (f). (NP-complete or NP-hard Write your design of a polynomial-time algorithm for this problem. h. i Analyze the algorithm in (h).