When a pure strain of tall plants (TT) with round seeds (RR) is crossed with a pure strain of short plants (tt) with wrinkled seeds (rr), an `F_(1)` generation is produced. The alleles for short and wrinkled are recessive to those for tall and round, respectively. When these `F_(1)` plants self-pollinate, what proportion of the `F_(2)` generation is short with wrinkled seeds ?