The luggage was …… heavy for him to lift A. much B. as C. so D. too

The correct answer is too.

• Much is used to compare quantities. For example, “I have much more money than you.”
• As is used to compare two things that are equal. For example, “I am as tall as you.”
• So is used to compare two things that are similar. For example, “I am so tired, I can’t go on.”
• Too is used to compare two things that are not equal. For example, “The luggage was too heavy for him to lift.”

In this case, the luggage was too heavy for the person to lift. This means that the luggage was heavier than the person was able to lift.