Gold in California in the 19th century. A. was discovered

B. has been discovered

C. was discover

D. they discovered

Gold (A.)was discovered in California in the 19th century.
Explanation:
"Was" is the correct past tense and the "ed" ending in "discovered" tells us it was discovered in the past

The answer is a because d and c don’t make sense in the sentence and b would be wrong because it wasn’t just discovered so it doesn’t make sense so that makes the answer a have a great day

Sometimes when you read things in your head, you skip overall small details/words. when you read aloud, you hear those words and it’s easier to comprehend what you just read. saying things aloud also you remember them.

What do you mean by this?