Select the most appropriate option to fill in blank number 5.
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. Sustain.
"Sustain" means to support, maintain, or keep something going, which fits perfectly in the context of supporting the planet's health through planting trees.
The other options don't match the intended meaning:
"Denigrate" means to criticize or belittle, which is the opposite of what the sentence is trying to convey.
"Complement" means to complete or enhance something, which doesn't fit in this context.
"Supplement" means to add something extra, which doesn't convey the idea of maintaining or supporting the planet.
Therefore, "sustain" is the most appropriate word here.