Excerpt from: Norse Mythology Part D

Kate McConnaughey

Then Loki, the spirit of evil, will break loose from the fetters with which the gods have bound him. (31) The frost giants join him. They will try to make a secret attack on the gods. But Heimdall, the sentry of heaven, will be on guard at the end of the rainbow-bridge. He needs no more sleep than a bird and can see for a hundred miles either by day or night.
Read the passage. Look at the underlined section marked number (31). There may be a mistake in the way the sentence is written. If you find a mistake, choose the answer that corrects the mistake. If there is no mistake, choose ‘Correct as is.’
A) Correct as is.
B) The frost giants joined him.
C) The frost giants will join him.
D) The frost giants could join him. I believe the answer is A.

No.

Read the preceding sentence carefully.

I believe you are mistaken The verb tenses don't match with the previous sentence. "Loki will break loose..."

Excerpt from: Norse Mythology Part A

Kate McConnaughey

(3)In his hand he carried a wonderful hammer which always had come back to his hand when he threw it.
How can sentence (3) be written to eliminate wordiness and redundancy without changing its original meaning?
A) The sentence is fine as is.
B) In his hand he carried a wonderful hammer.
C) He carried a hammer that returned to him when he threw it.
D) In his hand he carried a wonderful hammer that always returned.

To determine if there is a mistake in the underlined section and if there is, to choose the correct answer, we need to analyze the verb tense agreement in the sentence.

The original sentence states, "The frost giants join him."

Since the passage is written in future tense, describing events that will happen in the future, the verb tense should also be in future tense.

The correct answer is C) "The frost giants will join him."