The given pie charts show the proportion of literates and illiterates in a country, in the year 1970 and 1990,
and also the proportion of males (M) and females (F) among the literates. Which one of the following statements can be said to be true beyond any doubt?
(a) In 1970 half of the illiterates were ***** (females)
(b) The proportion of literate males to the total population of males remained the same over the years
(c) Male literacy did not improve over this **
(d) The ratio of female literates to male literates improved significantly over this **
