Amonohybrid cross is made between plants that

have experienced only one hybrid generation
differ in only one trait
are identical
are self-pollinated

SOS:

The answer is differ in only one trait!

The definition of monohybrid cross is "The breeding of two organisms which differ in a single trait."

Hope this helps!

the diploid number of chromosomes is sometimes represented by the symbol 2n. for the fruit fly, the diploid number is 8, which can be written as 2n = 8, where n represents twice the number of chromosomes in a sperm or egg cell.

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.