(b) Let us suppose, BB represents broad leaf and bb represents narrow leaf.  represents red flower colour and rr represents ivory. According to the question, red flower colour is incompletely dominant to ivory, therefore Rr will be pink coloured flowers. A cross between a plant which is heterozygous for both genes and true-breeding broad -leaved red - flowered plant is as follows:

Parents:

Gametes:  Br bR rr  BR

 generation:

From the above Punnett square, it is cleared that the expected proportion of broad - leaved plants with pink flowers amongst the offspring would be 2 in 4