By 2050, half the world's population may no longer have safe water to drink or grow food. ... More than 2 billion people lack safe drinking water. ... Most of the world's freshwater goes to agriculture, mainly to irrigating ... For example, it can take more water to grow biofuel crops than to consume fossil fuels.
A clause is a grammatical unit which express a complete proposition. that makes me decide to choose "verb" as the answer because in a clause it must have a subject and a predicate and usually under the predicate is the verb phrase.
