Answer:
The scouts baked twelve loafs of bread for the church festival.
Step-by-step explanation:
The plural form of the noun loaf is loaves. The reason is that nouns ending in -f have an irregular plural form: -ves. Other examples of nouns ending in -f with similar irregular plural forms are:
knife - knives
wife - wives
life - lives
The rest of the sentences contain correct irregular plural forms:
half - halves
foot - feet
tooth - teeth