Which of the following action or activity may causes undesirable effect to our environment?
i) Catching and keeping animals such as bird and cats at home.
ii) Feeding birds such as pigeon and crows in our neighbourhood.
iii) Burning unwanted plastic product in our neighbourhood o reduce non - biodegradable rubbish.
iv) Dumping biodegradable refuse such as fruit skins and bones in our sewage to make the water nutrients rich for healthy growth of flowering plants.