Which of the following is an r-selected species?

a)rat
b)humpback whale
c)eagle
d)elephant

it is a)

The correct answer is- A) Rat.

R selected species are those species that can survive in unstable, unpredictable environmental conditions and produce large number of small size offspring ( with low survival rate and no parental care).

These species grow very rapidly and attain reproductive maturity at early stage in their lives.

Example- Insects, rats.

On the contrary, B) , C), and D) are K selected species that survive under stable environmental conditions and produce large size offspring with very few number ( having long life span and parental care).

you need more balloons