What is the Doubling Up rule in your own words?

the doubling rule notes that if a one syllable word ends with a vowel and a consonant, double the consonant before adding the ending

i'm pretty sure i had this question the other day and b was the right answer.

b. and i with my fighting heart, i thought at

first / to steal up to him [the cyclops].   the cyclops’ actions first odysseus to take

action after killing his men and trapping in the cave revealed his intent of

doing them harm.   that is why odysseus

blinded him to enable him and his men to escape.