Which one of the following sequences was proposed by Darwin and Wallace for organic evolution?

In a gene pool,along with beneficial mutations,those mutations also exist which are damaging to an individual. It has been found that these mutations are often not eliminated from the population because:
$I.$ They have survival value.
$II.$ They are acquired.
$III.$ They are recessive and carried by heterozygous individuals.
$IV.$ They show genetic drift.
Choose the incorrect option$(s)$ regarding why these mutations persist in the gene pool.

When we say 'survival of the fittest',does it mean that $(a)$ those which are fit only survive,or $(b)$ those that survive are called fit? Comment.

Why do adaptations occur?

Explain the terms: $(i)$ Saltation and $(ii)$ Founder effect.

What does artificial selection in high-milk-yielding cows indicate?