Answer:
The three capitalization errors in the sentence below are river, North, and river. Their correct forms are indicated in bold letters.
The Missouri River...
north of St. Louis...
The Ohio River...
Step-by-step explanation:
Correct capitalization observes the rules below:
a) the first word of a sentence should be capitalized.
b) names and proper pronouns, for example, the Missouri River and the Ohio River, should be capitalized.
c) the word following a colon is not capitalized unless it is a name or a proper pronoun.
d) days, months, and holidays (not seasons) are capitalized.
e) most of the words in titles should be capitalized.