Which one of the following is used in preparing a natural mosquito repellent?

1. A

   Congress grass

   Congress grass. Parthenium; an invasive weed, not the citronella-type repellent.

2. B

   Elephant grass

   Elephant grass. Napier fodder.

3. C

   Lemongrass

   Lemongrass. Citronella/citral oil; a natural mosquito repellent.

4. D

   Nut grass

   Nut grass. Cyperus; a weed.

Summary. Official key is (c) lemongrass. Cymbopogon oils (citronella, citral) are the household natural mosquito repellent. The other three are grasses of other uses or weeds.