Questions

When modifiers are misplaced or put in the wrong place, things can get quite confusing. A modifier adds detail or limits or changes the meaning of another word or phrase. 

Here Option A) "Covered in fluffiness, the couple played with the kitten" is the ony sentence contains a misplaced modifier. In the sentence, it gives the meaning that the couple are fluffy not the kitten.

Ethernet uses Bus topology.

Valentina Tereshkova is the first woman to have flown into space

DNA is a very long chain polymer made up of thousands of repeating units called nucleotides.

Nucleotide Unit is composed of a phosphate group, a pentose sugar, and a nitrogenous base.

The sides of the DNA ladder are made up of alternating deoxyribose sugar -- phosphate group units.