To answer this question we need to analyze each available option:
A. Heterogamy: this refers to the difference in size of the gametes so is incorrect.
B. Conjugation: This type of genetic material exchange is typical of bacteria so is incorrect.
C. Gamete fusion: This refers to normal sexual reproduction when two gametes with different genetic loads combine to produce a zygote.
D. Fragmentation: This occurs when a hypha fragments and produces spores that germinate and generate a new individual with the same genetic load. So this is the correct answer.