Degree/intensity collocation – choose the adjective that best intensifies "lack of knowledge". Sentence: "I was astounded at his ______ lack of knowledge about the Continent of Africa." Select the most natural and emphatic adjective.

Given data

• We want a strong intensifier before "lack of knowledge".

Concept/Approach
Colossal collocates well with abstract nouns to indicate enormity (e.g., colossal ignorance, colossal mistake). The other choices are weaker/less idiomatic here.

Option analysis
colossal — best collocation: "colossal lack/ignorance." ✅abundant — positive connotation of plentiful supply; does not fit "lack".huge — possible but less idiomatic with "lack of knowledge".great — generic and weaker; "great lack" sounds odd.

Style tip
Common pairings: colossal ignorance, colossal blunder, colossal waste.

Final Answer
colossal