In the Section "Investigating Life: Birds Do It,Bees Do It",bumblebees

Multiple Choice

In the section "Investigating Life: Birds Do It,Bees Do It",bumblebees pollinated M.lewisii,whereas hummingbirds preferred the red-flowered M.cardinalis.If a hummingbird carries M.cardinalis pollen to M.lewisii,the resulting hybrid offspring are viable.M.lewisii and M.cardinalis are different species because of

A) post-zygotic barriers to reproduction.
B) pre-zygotic barriers to reproduction.
C) punctuated equilibrium.
D) gradualism.
E) asexual reproduction.