Which strategy would be most in determining the meaning of the word “scalpel”? replacing “scalpel” with the nearby synonym “blade” substituting the word “object” for the word “scalpel” using context clues “away from her gloved fingers” becoming familiar with prefixes, roots, and suffixes

Replacing it with blades because scalped are known as a surgical blades!

Betray, destroy, and obey do not need to be changed to add the suffix -ed, because the "y" at the end of each word is preceded by a vowel  (so  they would be spelled  "betrayed," "destroyed," and "obeyed").

but hurry is different; it has to  be spelled "hurried" because the "y" at the end of "hurry" is preceded by a consonant.