
Explanation:
Box 1: No
User1 is a Member and not a Guest Account, Access Review specified Guests only.
Box 2: No
User1 is a Member and not a Guest Account, Access Review specified Guests only.
Box 3: Yes
User3 can review the access guest users of Group1 which also includes Group2. UserB is the guest of Group2 and hence User3 can review the access of UserB.
Reference:
https://docs.microsoft.com/en-us/azure/active-directory/governance/create-access-review