Question one Explain the following in relation to virtual machines a) The concept of a virtual machine b) Hierarchical virtual machines c). Question oneExplain the following in relation to virtual machinesa) The concept of a virtual machineb) Hierarchical virtual machinesc) Intermediate languagesd) Security issues relating to running codes on alien machinesQuestion TwoA context-free grammar G has the following production represented in Backus-Naur Form (BNF):< exp > ? < exp > + < exp > | < exp > ? < exp > |< exp > ? < exp > | < exp > / < exp > |( < exp > ) | < number >< number > ? < digit > | < digit > < number >< digit > ? 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9.Write a leftmost derivation of 5 + 1 ? 4 * 8/4 then draw its equivalent parse tree