| Prickly pear cactus species introduced into Australia in |
| a) | 1920 | b) | 1930 |
| c) | 1925 | d) | 1929 |
| (a)The prickly pear cactus introduced into Australia in 1920s caused Havoc by spreading rapidly into million of hactares of range land. Finally invasive cactus was brought under control only after a cactus-feeding predator (a moth) from its natural habitat was introduced into the country |