Final answer:
The spelling rule for adding prefixes to root words is explained with examples for the prefixes un-, dis-, pre-, and bi-.
Step-by-step explanation:
The spelling rule for adding prefixes to a root word is as follows:
A) The prefix un- is added to a root word to indicate the opposite or lack of something. For example, the word 'happy' becomes 'unhappy' to indicate the opposite of happy.
B) The prefix dis- is added to a root word to indicate negation or reversal. For example, the word 'appear' becomes 'disappear' to indicate the action of not appearing or disappearing.
C) The prefix pre- is added to a root word to indicate something that happens before. For example, the word 'war' becomes 'prewar' to indicate something that happened before the war.
D) The prefix bi- is added to a root word to indicate two or twice. For example, the word 'cycle' becomes 'bicycle' to indicate a vehicle with two wheels.