Consider the sequence diagram given below for the use case "Record a book order' and answer the following questions. Record book order buger 1 findBook title of author or ISBN Find Book Uteme 1 listOfMatches (title, author...) addToCart (ISBN forbach book desired confirmation checkout faccount exists display Accountino (name, cc.) Open new account use case no account display Account Setup() Ino account) enter Accountinfo name, billingAddress.cc --> newAccount Confirmation 1 confirmPurchase PemailToSetler (purchaseinfo, purchaserinfo) email server a. Questions (5 marks) How many notes are used in above sequence diagram. List them. b. What is the purpose of vertical dotted lines and horizontal vertical arrows in above diagram? Explain the second use case (provided in bottom rectangle in diagram) in your own words based on the messages provided