Mass Communication and Journalism 2017 Solved Paper

1970 is an ordinary year. We know that the calendar of an ordinary year repeats after 6 yr or 11 yr.
6 yrs after 1970 is 1976 and 11 yr after 1970 is 1981. In the given options, we have only year 1981.
So, we can easily eliminate rest of the options. Now, it is clear that her birthday would fall again on Sunday in 1981.