When two heterozygous individual are crossed, the proportion of the offspring that are true breeding for dominant trait is ​

75%

Explanation:

If you drew a Punnett Square, you will see that the possible outcomes would be AA, Aa, aA, and aa. Three out of the four would exhibit the dominant trait.

answer; i believe the answer is (polygenic inheritance;

yes? sounds right, but you didn’t ask a question.