Multi-choice problem: Choose from the options at the end, and answer how do you do this: Help straggly petunias to grow new lush flowers.

OPTIONS: -Petunias will get long and straggly and stop producing flowers unless you cut the roots back about one third, about once a month. This will generate lush new growth all summer long.; -Petunias will get long and straggly and stop producing flowers unless you cut the foliage back about one third, about once a month. This will generate lush new flowers all summer long.;
Petunias will get long and straggly and stop producing flowers unless you cut the foliage back about one third, about once a month. This will generate lush new flowers all summer long.