Final answer:
To make 3 dozen cookies, Greg would need 3/5 of the sugar required for 5 dozen cookies.
Step-by-step explanation:
To find out how much sugar Greg would need to make 3 dozen cookies, we need to determine the fraction of sugar required for 3 dozen compared to 5 dozen.
Since 3 dozen is less than 5 dozen, Greg would need less sugar. Therefore, the correct answer is a) 3/5 of the sugar required for 5 dozen cookies.