Paramecium aurelia has a higher rate of population growth and can tolerate a hig

Gause and the Principle of Competitive Exclusion:

In classic experiments carried out in 1934 and 1935, Russian ecologist G. F. Gause studied competition among different species of Paramecium, a tiny protist. When Gause grew P. aurelia together with P. caudatum in the same culture tube, the numbers of P. caudatum always declined to extinction, leaving P. aurelia the only survivor. Gause found P. aurelia was able to grow six times faster than its competitor P. caudatum because it was able to better utilize the limited available resources, an example of exploitative competition. From experiments such as this, Gause formulated what is now called the principle of competitive exclusion. This principle states that if two species are competing for a limited resource, the species that uses the resource more efficiently will eventually eliminate the other locally no two species with the same niche can coexist when resources are limiting.

Based on this information the option, b. Initially increased, after which P. aurelia thrived and P. caudatum died out is correct.