What are the federal gift tax consequences of the following?

a) Sally, a widow, who has made no prior taxable gifts, gave her adult son John $13,500 outright.

b) Henry gives $13,000 to each of six adult family members.

c) Jane, a widow who has made no taxable gifts, gives her adult daughter Melissa $23,000 outright in each of two successive years.

d) Dan, a widower, has made no prior taxable gifts, gave his daughter and son in law $28,000 gift to use as a down payment on a house.